Clinical outcome after reconstruction of the medial patellofemoral ligament in patients with recurrent patella instability

Fear of Reinjury, Psychological Factors, and Sport Played Have Negative Impact on Return to Sport Following Medial Patellofemoral Ligament Reconstruction for Patellar Instability

PURPOSE

To analyze factors that affect return to sport after medial patellofemoral ligament reconstruction (MPFLR), such as psychological factors, sport played, and a positive apprehension test following surgery, and to determine the average return to sport rates and time to return to sport.

METHODS

A literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies met the following criteria: patients underwent MPFLR for patellar instability, return to sport was recorded, and a factor that affected return to sport was mentioned. Search terms included medial patellofemoral ligament, tibial tubercle osteotomy, tibial tubercle transfer, return to play, and return to sport.

RESULTS

Eighteen of 632 identified studies met inclusion criteria, and 1,072 patients who underwent MFPLR were recorded. Return-to-sport rates and mean/median time ranged from 60.0% to 100% and 3 to 10.4 months, respectively. Of the patients, 55.6% to 84.0% returned to sport without decreasing the level of competition. Six of 12 studies (50.0%) reported fear of reinjury as the top reason for patients not returning or returning at a lower level of sport. Volleyball/handball had the lowest return to the same level following surgery (18.2%-50.0%).

CONCLUSIONS

Athletes who underwent MPFLR following recurrent patellar instability returned to sport at a range of 60.0% to 100%. Return to sport at the same level or higher was found to have a lower maximum rate at 55.6% to 84.0%. Fear of reinjury and sport played were found to have a substantial impact on ability to return to sport. Surgeons can use this information to advise patients on expectations following surgery.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Radiographic Landmark Measurements for the Femoral Footprint of the Medial Patellofemoral Complex May Be Affected by Visible Femoral Shaft Length on Lateral Knee Radiographs

PURPOSE

To assess the effect of visible femoral shaft length on the accuracy of radiographic landmarks of the medial patellofemoral complex (MPFC).

METHODS

In 9 cadaveric knees, the MPFC footprint was exposed on the medial femur, and its proximal and distal boundaries were marked. Lateral fluoroscopic images of the knee were assessed in 1-cm length increments, beginning 1 cm proximal to the medial condyle and continuing proximally to 8 cm. The MPFC midpoint was described on each image relative to the posterior cortical line of the femur and a line perpendicular to this line through the proximal margin of the medial condyle. In addition, the MPFC midpoint was assessed relative to a line from the proximal posterior cortex to the midpoint of Blumensaat line.

RESULTS

Using the posterior cortical line as a reference, the MPFC radiographic landmark moved anteriorly with decreasing visible femoral shaft on radiographs, particularly at 4 cm and less. However, no proximal-distal change was noted. Linear regression analysis demonstrated a relationship between visible femoral shaft and MPFC position on radiographs (R = 0.461, R2 = 0.212, B = -0.636, P < .001). For every centimeter decrease in the visible femoral shaft, the radiographic MPFC footprint moved anteriorly by 0.636 mm. Receiver operating characteristic curve analysis revealed that a minimum of 4 cm of femoral shaft on lateral radiographs is required for accurate MPFC footprint localization (area under the curve = 0.80; sensitivity = 76.7%; specificity = 69.0%; P < .001). In contrast, no anterior-posterior change was seen when referencing a line from the proximal posterior cortex to the midpoint of Blumensaat line.

CONCLUSIONS

When using the posterior cortical line to identify the midpoint of the MPFC, at least 4 cm of femoral shaft should be visible for accurate assessment. If less than 4 cm of shaft is visible, a line through the midpoint of Blumensaat line and the proximal posterior cortex can be used as an alternative method to estimate the position of the femoral footprint.

CLINICAL RELEVANCE

As fluoroscopy is frequently used intraoperatively for MPFC reconstruction, our findings may serve as a guide when assessing femoral tunnel placement on fluoroscopy.

MPFL Reconstruction Combined with a Modified Elmslie-Trillat Procedure for Recurrent Patellofemoral Instability

Several combined procedures have been reported for treating recurrent patellofemoral instability (RPI) with various types and severity of morphological abnormalities, but none have identified absolute threshold values as indications for surgery. We performed medial patellofemoral ligament (MPFL) reconstruction combined with a modified Elmslie-Trillat (ET) procedure on 24 knees (10 male and 11 female patients) to treat RPI with morphological abnormalities corresponding to elevated tibial tubercle-trochlear groove (TT-TG) distance, significant patella alta, and trochlear dysplasia. The inclusion criteria were RPI with morphological abnormalities corresponding to one or more of the following: sulcus angle > 160 degrees, trochlear dysplasia of Dejour classification C or D, Caton-Deschamps index > 1.5, lateral shift ratio > 50%, congruence angle > 15 degrees, or TT-TG distance > 20 mm, including habitual dislocation of the patella. Skeletally immature patients and those with congenital dislocation of the patella were excluded. The Kujala score, International Knee Documentation Committee subjective score, Knee Injury and Osteoarthritis Outcome score (KOOS), and each item of the KOOS improved significantly after surgery. Patellar apprehension sign was present preoperatively in all cases, but all disappeared postoperatively. No instance of postoperative redislocation was observed. On radiographic examination, the mean Q angle, tilting angle, lateral shift ratio, congruence angle, Caton-Deschamps index, Insall-Salvati index, and TT-TG distance improved significantly after surgery. There were no significant differences in sulcus angle after surgery. These results suggest MPFL reconstruction combined with a modified ET procedure provides satisfactory outcomes based on radiological and clinical evaluations for RPI with morphological abnormalities corresponding to elevated TT-TG distance, significant patella alta, and trochlear dysplasia.

Does Tibial Tuberosity Osteotomy Improve Outcomes When Combined With Medial Patellofemoral Ligament Reconstruction in the Presence of Increased Tibial Tuberosity-Trochlear Groove Distance? A Systematic Review and Meta-analysis

Background

There has been recent debate regarding the optimal surgical management strategy for recurrent patellofemoral instability in the presence of an increased tibial tuberosity-trochlear groove (TT-TG) distance. In particular, performing a combined tibial tuberosity osteotomy (TTO) and medial patellofemoral ligament reconstruction (MPFLR) for patients with a TT-TG >20 mm has been questioned, with the hypothesis that an isolated MPFLR (iMPFLR) would be just as effective.

Purpose

To pool and compare outcomes after MPFLR+TTO versus iMPFLR in patients with a TT-TG >20 mm.

Study Design

Systematic review; Level of evidence, 4.

Methods

PubMed-MEDLINE, Embase, Web of Science, and Cochrane Central were searched, and a systematic review was performed. Included were studies that reported postoperative redislocation rates and/or functional outcome scores for patients with recurrent patellar instability and a TT-TG >20 mm who underwent either MPFLR+TTO or iMPFLR and had minimum 2-year follow-up data. Methodologic quality was assessed using the modified Coleman Methodology Score (mCMS). A proportional meta-analysis comparing redislocation, subjective instability, and total complication rates was performed, and mean postoperative functional outcome scores were pooled using a random-effects model with a restricted maximum likelihood estimator.

Results

In total, 1548 studies were screened, from which 13 were included for analysis. Of the 386 included patients (406 knees), 276 underwent MPFLR+TTO and 110 underwent iMPFLR. The mean mCMS was 61.3 ± 10.5 (range, 48-77). The pooled postoperative redislocation rate was 1.22% (95% CI, 0.22%-7%), with no significant difference between the study groups (P = .9995). The pooled complication rate was 10.17% (95% CI, 6.2%-16.3%) with no difference between groups (P = .9275), although the MPFLR+TTO group had higher heterogeneity in complication rates (I2 = 79.4%) compared with iMPFLR (I2 = 0%). There was no group difference in the pooled postoperative Lysholm scores (P = .5177), but patients who underwent iMPFLR had significantly higher postoperative Kujala scores compared with those who underwent MPFLR+TTO (P = .0283).

Conclusion

Even in the presence of previously indicative anatomic factors (TT-TG >20 mm), TTO combined with MPFLR does not seem to confer additional benefit compared with iMPFLR. This finding could be advantageous in minimizing the burden of additional surgery with its associated risks. The study findings should, however, be interpreted with caution given the heterogeneity of the studies.

Sulcus deepening trochleoplasty versus bereiter trochleoplasty for high grade trochlear dysplasia: A systematic review and meta-analysis for clinical outcome and recurrent instability

BACKGROUND

Trochlear dysplasia is a condition in which the femoral trochlea has an abnormal shape and function. Trochleoplasty aims to change the shape of the trochlea in order to stabilize an unstable patella. This study compared clinical outcomes and recurrent instability after surgery between sulcus deepening trochleoplasty (Lyon) and Bereiter trochleoplasty in patients with high-grade trochlear dysplasia.

METHODS

We conducted a meta-analysis comparing Bereiter and Lyon trochleoplasty based on PRISMA guidelines regarding clinical outcome and recurrent instability for high-grade trochlear dysplasia. Searching on five databases, we found 11 eligible studies with a total of 520 subjects to be analysed. Studies were qualitatively and quantitatively evaluated using Review Manager 5.4 or equivalent.

RESULTS

Both techniques showed no differences in sulcus angle, return-to-sport rate, and satisfactory rate. The IKDC and Kujala scores showed good outcomes but were not significantly different. IKDC score was not different after analysis between Bereiter and Lyon techniques. The pooled improvement of IKDC score on both subgroups was 24.39 (95% CI 21.14-27.65). A pooled analysis of 10 studies found that the Kujala score did not differ between groups with Bereiter and Lyon techniques. The total pooled mean difference of both groups was 25.87 (95% CI 21.70-30.05).

CONCLUSION

None of the techniques analysed highlighted an absolute superiority. Clinical relevance showed both techniques have good clinical outcomes, fewer complications, and recurrent instability for high-grade trochlear dysplasia.

Double-Limb Graft Versus Single-Limb Graft Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation: A Meta-analysis of Randomized Controlled Trials and Cohort Studies

BACKGROUND

The medial patellofemoral ligament (MPFL) is the most important stabilizer of lateral dislocation of the patella. Single-limb (SL) and double-limb (DL) graft MPFL reconstructions have been increasingly used to treat recurrent patellar dislocations, but the clinical efficacy of SL versus DL graft MPFL reconstructions remains controversial owing to the inconsistent conclusions of previous studies.

PURPOSE

This study aimed to compare the clinical outcomes of SL and DL graft MPFL reconstructions for patients with recurrent patellar dislocation by conducting a meta-analysis of randomized controlled trials and cohort studies.

STUDY DESIGN

Meta-analysis; Level of evidence, 3.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for relevant studies. The retrieval time was up to July 25, 2022. Two evaluators independently screened the literature, extracted data, and assessed the methodological quality of the enrolled studies. Meta-analysis was conducted using RevMan 5.4 software.

RESULTS

A total of 4 randomized controlled trials and 3 cohort studies with 451 patients were included. The joint stability and functional scores in both groups improved significantly from baseline. When compared with SL graft reconstruction, DL graft reconstruction provided reduced recurrent instability (P = .01), anterior patella-related pain (P = .02), and patellar lateral shift rate (P = .02). Regarding functional recovery, patients undergoing DL graft reconstruction presented better scores on the Kujala (P < .001), Tegner (P = .009), and International Knee Documentation Committee (IKDC) (P < .001) but similar Lysholm scores as compared with SL graft reconstruction. No statistically significant difference was found between the techniques in the reduction of the patellar tilt angle, complications other than anterior patella-related pain, or postoperative pain.

CONCLUSION

When compared with SL graft MPFL reconstruction, DL graft MPFL reconstruction yielded better outcomes in terms of postoperative recurrent instability, anterior patella-related pain, patellar lateral shift rate, Kujala score, Tegner score, and IKDC score. The amount of high-quality evidence is insufficient, so this conclusion should be interpreted with caution.

Clinical Insights into the Treatment of Patellofemoral Instability with Medial Patellofemoral Ligament Reconstruction: Pearls and Pitfalls-Lessons Learned from 20 Years

Patellofemoral instability is a prevalent cause of pain and disability in young individuals engaged in athletic activities. Adolescents face a particularly notable risk of patellar dislocation, which can be attributed to rapid skeletal growth, changes in q-angle, ligamentous laxity, higher activity levels, and increased exposure to risk. Specific sports activities carry an elevated risk of patellar dislocation. Younger age and trochlear dysplasia present the highest risk factors for recurrent patellar dislocations. International guidelines recommend conservative therapy following a single patellar dislocation without osteochondral lesions but suggest surgical intervention in recurrent cases. In this study, we have compiled current scientific data on therapy recommendations, focusing on MPFL (medial patellofemoral ligament) reconstruction. We discuss patient selection, surgical indications, graft selection, location and choice of fixation, graft tensioning, and postoperative care.

Functional outcomes after Medial Patellofemoral Ligament Reconstruction show inverted J-shaped relation with Body Mass Index

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is a recognised surgical procedure for the treatment of recurrent patellofemoral instability with excellent outcomes reported. The aim of this study is to determine if body mass index can influence these outcomes.

METHODS

This is a single-centre retrospective analysis of a longitudinal patellofemoral database. Patients with recurrent patellar instability, without patellar alta or severe trochlear dysplasia were treated using a MPFL-R between 2015 and 2019 at The Robert Jones & Agnes Hunt Orthopaedic Hospital. The clinical efficacy following surgery was assessed by Kujula, International Knee Documentation Committee Score (IKDC), and EuroQol-5 score (EQ-5D) at baseline and up to 26 months post-operatively; their safety assessed by complication rate and requirement for further surgery. The effect of Body Mass Index (BMI) on clinical outcome was analysed using linear, curvilinear, and segmented models following propensity score weighting.

RESULTS

A total of 97 patients (97 Knees, mean age 25y) were analysed. Of these, 61 patients had a BMI < 30 kg/m² (mean age 23y, mean BMI 24) of which 7 patients (12.3%) required additional surgery. A further 36 patients had a BMI > 30 kg/m² (mean age 27y, mean BMI 36) of which 2 patients (5.6%) required additional surgery. The re-dislocation rate was 0% in each BMI group. Both groups had a significantly improved mean outcome following surgery, with improvements in mean IKDC above the minimum clinical important differences (MCID) of 20.5. BMI had an inverted J-shaped association with functional outcome, showing peak outcomes at BMI of 20.5 (95% CI 18.5 to 22.4; IKDC and Kujala) or BMI of 28 (EQ-5D index). No evidence for an association between BMI and complication risk was found.

CONCLUSION

BMI influences the functional outcomes in MPFL-R with an inverted J-shaped relation, without evidence it affected the complication or re-dislocation rate. In the absence of patella alta and severe trochlear dysplasia, an isolated MPFL reconstruction is a safe and effective procedure to treat patellar instability, with the best functional outcome in patients with a BMI around 20 to 21.

LEVEL OF EVIDENCE

Level III.

At 10-Year Minimum Follow-Up, One-Third of Patients Have Patellofemoral Arthritis After Isolated Medial Patellofemoral Ligament Reconstruction Using Gracilis Tendon Autograft

PURPOSE

To report the long-term clinical outcomes after isolated medial patellofemoral ligament reconstruction (MPFLr) to treat recurrent patellar instability.

METHODS

This was a single-center study of patients undergoing an isolated MPFLr between 2000 and 2011. All patients underwent reconstruction using hamstring autograft. The inclusion criteria were a minimum 10-year follow-up period and skeletally mature patients with more than 1 episode of patellar dislocation who underwent MPFLr without an associated bony procedure.

RESULTS

A total of 54 knees were available for final analysis. The mean follow-up period was 12.3 years (range, 10-14 year). The mean age at surgery was 25 years. No patients had patellofemoral arthritis (PFA) prior to surgery. Preoperatively, the mean Caton-Deschamps index was 1.1 and the mean tibial tubercle-trochlear groove distance was 14.9 ± 2 mm (range, 7-17 mm). All patients had trochlear dysplasia according to the Dejour classification. At final follow-up, the mean Kujala score was 82.9 ± 15.3; mean International Knee Documentation Committee score, 78.3 ± 18.5; and mean Tegner score, 4.0 ± 1.7. Patients with an unsatisfactory outcome as determined by a Kujala score lower than 80 had a higher Caton-Deschamps index preoperatively and were more likely to be female patients; however, neither factor reached significance. Of the patients, 33 (66%) had no radiographic evidence of PFA whereas 15 (30%) had Iwano stage 1 and 2 had Iwano stage 2 (4%). At final follow-up, 4 patients (7.4%) had recurrent instability requiring revision surgery.

CONCLUSIONS

Isolated MPFLr with gracilis tendon autograft in appropriately selected patients is an effective long-term treatment for recurrent patellofemoral instability with low rates of recurrence. One-third of patients exhibit radiographic evidence of PFA more than 10 years after isolated MPFLr.

LEVEL OF EVIDENCE

Level IV, case series.

Medial Patellofemoral Ligament Reconstruction in Obese Patients Results in Low Complication Rates and Improved Subjective Outcomes

Purpose

To compare outcomes, activity scores, and complication rates of obese and non-obese patients undergoing medial patellofemoral ligament (MPFL) reconstruction.

Methods

A retrospective review identified patients undergoing MPFL reconstruction for recurrent patellofemoral instability. Patients were included if they had undergone MPFL reconstruction and had follow-up for a minimum of 6 months. Patients were excluded if they underwent surgery less than 6 months earlier, had no outcome data recorded, or underwent concomitant bony procedures. Patients were divided into 2 groups based on body mass index (BMI): BMI of 30 or greater and BMI less than 30. Presurgical and postsurgical patient-reported outcomes including Knee Injury and Osteoarthritis Outcome Score (KOOS) domains and the Tegner score were collected. Complications requiring reoperation were recorded. P < .05 was defined as a statistically significant difference.

Results

A total of 55 patients (57 knees) were included. There were 26 knees with a BMI of 30 or greater and 31 knees with a BMI less than 30. There were no differences in patient demographic characteristics between the 2 groups. Preoperatively, no significant differences were found in KOOS subscores or Tegner scores (P = .21) between groups. At minimum 6-month follow-up (range, 6.1-70.5 months), patients with a BMI of 30 or greater showed statistically significant improvements in the KOOS Pain, Activities of Daily Living, Symptoms, and Sport/Recreation subscores. Patients with a BMI less than 30 showed a statistically significant improvement in the KOOS Quality of Life subscore. The group with a BMI of 30 or greater had significantly lower KOOS Quality of Life (33.34 ± 19.10 vs 54.47 ± 28.00, P = .03) and Tegner (2.56 ± 1.59 vs 4.78 ± 2.68, P = .05) scores. Complication rates were low, with 2 knees (7.69%) requiring reoperation in the cohort with a BMI of 30 or greater and 4 knees (12.90%) requiring reoperation in the cohort with a BMI less than 30, including 1 reoperation for recurrent patellofemoral instability (P = .68).

Conclusions

In this study, MPFL reconstruction in obese patients was safe and effective, with low complication rates and improvements in most patient-reported outcomes. Compared with patients with a BMI less than 30, obese patients had lower quality-of-life and activity scores at final follow-up.

Level of Evidence

Level III, retrospective cohort study.

Patellofemoral articular cartilage damage is associated with poorer patient-reported outcomes following isolated medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to investigate the impact of articular cartilage damage on outcomes following medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Record review identified 160 patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. Patient demographics, patellofemoral articular cartilage status at surgery, and patient anatomical measures from imaging were obtained via chart review. Patients were contacted and outcomes assessed through collection of Norwich Patellar Instability (NPI) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score as well as an assessment for recurrent patellar dislocation. Outcomes of patients with grade 0-II patellofemoral cartilage damage were compared to those of patients with grade III-IV cartilage damage.

RESULTS

One hundred twenty-two patients (76%) with a minimum of one year follow-up were contacted at a mean of 4.8 years post-operatively. A total of 63 patients (52%) had grade III or IV patellofemoral chondral damage at the time of surgery. The majority of the defects was on the medial patella (46 patients-72%) and the mean patellar defect size was 2.8 cm². Among 93 patients who completed patient-reported outcome scores, the 52 with grade III or IV chondral damage reported a significantly poorer KOOS Quality of Life than the 44 patients with grade 0 to II chondral damage (p = 0.041), controlling for patient age, sex, BMI, and anatomical factors.

CONCLUSION

Patients with grade III or IV articular cartilage damage of the patellofemoral joint at the time of MPFL reconstruction demonstrated poorer KOOS knee-related quality of life than patients without grade III or IV articular cartilage damage at a mean of 4.8 years following isolated MPFL reconstruction.

LEVEL OF EVIDENCE

Level II.

Patellar Instability

➢

Certain anatomic factors, such as patella alta, increased tibial tubercle-trochlear groove distance, rotational deformity, and trochlear dysplasia, are associated with an increased risk of recurrent patellar instability.

➢

The presence of a preoperative J-sign is predictive of recurrent instability after operative management.

➢

Isolated medial patellofemoral ligament reconstruction may be considered on an individualized basis, considering whether the patient has anatomic abnormalities such as valgus malalignment, trochlear dysplasia, or patella alta in addition to the patient activity level.

➢

More complex operative management (bony or cartilaginous procedures) should be considered in patients with recurrent instability, malalignment, and certain anatomic factors.

Age, body mass index, female gender, and patellofemoral cartilage degeneration predict worse patient outcome after patellofemoral instability surgery

PURPOSE

To evaluate predicting factors for patient-reported outcomes and revision interventions following surgical treatment of patients with patellofemoral instability.

METHODS

From a prospective database at the university Orthopedic Department, 138 knees from 116 patients who underwent patellofemoral instability surgery (2012-2019) were enrolled in a retrospective analysis: 34 cases of isolated MPFLrec; 92 cases of MPFLrec plus tibial tuberosity transfer; and 12 cases of MPFLrec plus trochleoplasty. Patient-reported outcome measures were recorded for knee-specific function (KOOS), general quality of life (EQ-5D), and activity level (Tegner scale). Post-operative revision interventions were also actively recorded. As potential predicting factors, patient demographic (gender, age, BMI) and radiographic (pre-operative: patellar height and tilt, tibial tuberosity-trochlear groove distance, trochlear dysplasia, knee osteoarthritis; post-operative: MPFL insertion point; intra-operative: isolated vs. combined procedures, chondropenia severity score) parameters were analyzed using multivariate linear regression models.

RESULTS

With median follow-up of 4.4 (1.0-8.9) years, all patient-reported outcome measures had significantly improved from pre-operative levels: KOOS cumulative, from 71 (15) to 78 (16); EQ-5D, from 0.68 (0.20) to 0.78 (0.21); and Tegner activity scale, from 3 (0-10) to 4 (0-10). No patellofemoral instability revision procedures were performed. One-fifth (27/138) of the operated knees required second surgical interventions, predominately due to hardware or arthrofibrosis. Patients who required post-operative knee manipulation under anesthesia or arthroscopic debridement showed lower post-operative improvement for KOOS cumulative and EQ-5D. Age, BMI, patellofemoral knee osteoarthritis, and shorter follow-up time revealed significant negative correlations to some of the post-operative KOOS subscales. Age was negatively correlated to post-operative EQ-5D, while post-operative Tegner activity scale was negatively correlated to female gender and patellofemoral chondropenia severity score. Femoral MPFL insertion point revealed no association with any outcome measures.

CONCLUSION

Patellofemoral instability surgery for isolated or combined MPFLrec is safe and substantially improves knee function and patient quality of life and activity levels. Serious adverse events are rare, with no recurrent patellofemoral instability. Patients who required post-operative knee manipulation or arthroscopic debridement showed less improvement in subjective measures of treatment outcomes. Older age, higher BMI, worse pre-operative patellofemoral cartilage status, and female gender had negative effects on outcome.

LEVEL OF EVIDENCE

III.

Landmarks Used in Medial Patellofemoral Ligament Reconstruction Have Variable Topography

Purpose

To describe the morphology of the adductor tubercle (AT), medial epicondyle (ME), and gastrocnemius tubercle (GT); to quantify their relationships to the medial patellofemoral ligament (MPFL) footprint location; and to classify the reliability of each landmark based on measurement variability.

Methods

Eight cadaveric specimens were dissected to expose the following landmarks on the femur: MPFL footprint, AT, ME, and GT. Using the MicroScribe 3D digitizer, each landmark was projected into a 3-dimensional coordinate system and reconstructed into a complex, closed polygon. For each specimen tubercle, the base surface area, volume, height, base:height ratio, sulcus point, and distance from the MPFL footprint center were calculated. Levene's test was performed to evaluate differences in variance of the morphologic parameters between the three osseous structures.

Results

The ME had significantly greater variance in volume than the GT (P = .032), and the AT (17.5 ± 3.9) and GT (19.5 ± 3.6) were significantly less variable in base:height ratio than the ME (95.3 ± 19.2; P < .001). The GT was the closest to the MPFL footprint center (7.1 ± 3.1 mm) compared with the AT (13.4 ± 3.6 mm, P = .002) and ME (13.2 ± 2.7 mm, P = .003). However, the tubercles were equally variable in terms of distance to the MPFL footprint center (P = .86). Lastly, the sulcus point was estimated to be on average 1.9 ± 2.9 mm distal and 2.0 ± 2.0 mm posterior to the MPFL center point.

Conclusions

The 3 major osseous landmarks of the medial femur have significantly different variances in volume and base:height ratio. Specifically, the variability and elongated morphology of the ME differentiated this landmark from the AT and GT, which demonstrated the most consistent morphology.

Clinical Relevance

The results of this study may be useful to accurately locate landmarks for femoral tunnel placement and determine the isometric MPFL point during reconstruction.

Isolated medial patellofemoral ligament reconstruction results in similar postoperative outcomes as medial patellofemoral ligament reconstruction and tibial-tubercle osteotomy: a systematic review and meta-analysis

PURPOSE

To determine the effect of isolated medial patellofemoral ligament reconstruction (MPFLR) versus concomitant MPFLR and tibial-tubercle osteotomy (TTO) on patient-reported functional outcomes, rate of patellar redislocation, and rate of return to sport in skeletally mature patients with recurrent patellar instability and lateralization as defined by elevated tibial-tubercle trochlear groove (TT-TG) distance.

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to July 10th, 2022 for literature outlining the management of patients with TT-TG indices greater than 15 mm with either isolated MPFLR or concomitant MPFLR and TTO procedures. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on functional outcomes via the Kujala anterior knee pain score, redislocation rates, return to sport rates, and complications were recorded. The MINORS score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 31 studies comprising 1405 patients (1452 knees) were included in this review. The mean Kujala score in 13 studies comprising 848 total patients in the isolated MPFLR group was 85.0 (range 80.9-97.5) compared to a score of 83.7 (range 77.2-94.0) in 14 studies comprising 459 patients in the concomitant group. The mean pooled redislocation rate in 19 studies examining isolated MPFLR procedures comprising 948 patients was 3.1% (95% CI 2.1-4.4%, I² = 7%) as opposed to 3.2% (95% CI 1.9-5.0%, I² = 0%) in 15 studies comprising 486 patients in the concomitant group. The mean pooled return to sport rate in seven studies with 472 total patients in the isolated MPFLR group was 82% (95% CI 78-86%, I² = 16%) compared to a score of 92% (95% CI 78-99%, I² = 58%) in four studies comprising 54 patients in the concomitant group. There were similar complication rates between both treatment groups, including range of motion deficits, fractures, infections, and graft failures.

CONCLUSION

Isolated MPFLR leads to similar anterior knee pain, similar redislocation rates and lower return to sport rates than concomitant MPFLR and TTO procedures in patients with TT-TG distances greater than 15 mm. Information from this review can aid surgeons in their decision to choose MPFLR versus concomitant procedures for this patient population, and can also guide future studies on this topic.

LEVEL OF EVIDENCE

Level IV.

Quality of life following medial patellofemoral ligament reconstruction combined with medial tibial tubercle transfer in patients with recurrent patellar dislocation: a retrospective comparative study

Background

Because the patients undergoing medial patellofemoral ligament reconstruction (MPFLr) combined with medial tibial tubercle transfer (TTT) procedure are usually young and active, the quality of life (QoL) is also an important prognostic factor for patients with recurrent patellar dislocation. Assessing QoL can provide more useful and accurate evidence for the effects of this procedure. This study aimed to evaluate QoL following MPFLr combined with TTT, compared with isolated MPFLr (iMPFLr).

Methods

Fifty-one patients who underwent iMPFLr + TTT and 48 patients who underwent iMPFLr were included. Clinical evaluation included QoL (EQ-5D-5L and EQ-5D VAS), functional outcomes (Kujala, Lysholm and Tegner activity scores), physical examinations (patellar apprehension test and range of motion) and redislocation rates. Radiological evaluation included patellar tilt angle and bisect offset. These preoperative and postoperative results were compared between groups at baseline and the final follow-up. The paired and independent t tests were used for the data following a normal distribution. Otherwise, the Wilcoxon and Mann–Whitney U tests were used to analyze the differences. Categorical variables were compared by chi-square or Fisher’s exact test.

Results

All of the QoL (EQ-5D-5L and EQ-5D VAS), clinical results and radiological outcomes significantly improved in both groups at the final follow-up, with no significant differences between groups. There was no significant difference in five dimensions of EQ-5D at the final follow-up, although percentages of people with problems of mobility and pain/discomfort were higher in the MPFLr + TTT group. Female patients had lower EQ-5D index and EQ-5D VAS compared with male patients in both groups at the final follow-up, but there was only a significant difference in the EQ-5D VAS.

Conclusions

Both MPFLr + TTT and iMPFLr groups obtained similar and satisfactory improvements in the QoL, clinical results and radiological outcomes, indicating that MPFLr combined with TTT is a safe and effective procedure, which can significantly improve the QoL for patients with recurrent patellar dislocation in cases of pathologically lateralized TT. However, female patients obtained lower QoL than males.

Three-dimensional transfer of tibial tuberosity for patellar instability with patella alta preserves patellar position and clinical outcomes: A minimum 3-year follow-up study

BACKGROUND

The three-dimensional (3D) transfer of tibial tuberosity has been reported to improve patellofemoral congruity and showed good clinical outcomes during the short follow-up, however, little is known about whether the patellar position and clinical outcomes are preserved at longer follow-ups and the risk factors for poor clinical outcomes.

HYPOTHESIS

We hypothesized that patellar position and clinical outcomes would be preserved and the predisposing factors were associated with poor clinical outcomes after the 3D transfer of tibial tuberosity.

PATIENTS AND METHODS

Thirty-nine patients, with a mean age of 27.9 (15-52) years, who underwent the 3D transfer of the tibial tuberosity were enrolled. Patellar position was evaluated using the Caton-Deschamps index and patellar tilt. Clinical outcomes were evaluated with Lysholm and Kujala scores pre- and postoperatively. Age, body mass index (BMI), radiographic measurements, and range of motion (ROM) were compared between the poor group (defined as <80 points on Kujala score) and the good group (≥80 points). The mean follow-up period was 54.1 (36-100) months.

RESULTS

Patellar position decreased from 1.32 (1.21-1.53) preoperatively to 0.99 (0.84-1.07) at the final follow-up, according to the Caton-Deschamps index (p < 0.01). The mean patellar tilt decreased from 26.0° (21-40°) to 15.1° (5-28°) (p < 0.01). Kujala and Lysholm scales improved from 59.1 to 54.2 to 90.1 and 91.8 at final follow-up, respectively (p < 0.01). Increased BMI, lower femorotibial angle, limited ROM, and poor preoperative clinical outcomes were the predicting factors for poor postoperative clinical outcomes (p < 0.05).

CONCLUSION

The 3D transfer for patellar instability with patella alta preserved the patellar position and clinical outcomes for at least 3 years. Predisposing factors that may potentially affect postoperative clinical outcomes of the 3D transfer of tibial tuberosity include an increased BMI, valgus knee, limited ROM, and poor preoperative clinical outcomes.

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BACKGROUND

Trochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty.

METHODS

Between 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient's latest follow-up assessment.

RESULTS

The mean age at operation was 22y (SD ± 4.7, range 14-37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12-60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m²) was associated with inferior outcomes.

CONCLUSION

Trochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.

Radiographic Landmarks for the Femoral Attachment of the Medial Patellofemoral Complex: A Cadaveric Study

PURPOSE

To report the radiographic landmarks for the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the radiographic positions corresponding to the medial quadriceps tendon femoral ligament (MQTFL) and medial patellofemoral ligament (MPFL) fibers.

METHODS

In 8 unpaired cadaveric knees, the MPFC footprint was exposed on the medial femur, and the proximal and distal boundaries of the footprint were marked. Lateral fluoroscopic images of the knee were obtained and analyzed using Image J. The proximal boundary corresponding to the MQTFL, the MPFC midpoint, and distal boundary corresponding to the MPFL were described radiographically and compared for differences in position.

RESULTS

The proximal MQTFL footprint was 0.8 ± 0.6 mm anterior (P = .013) and 5.2 ± 1.8 mm proximal to the MPFC midpoint (P <.001), whereas the distal MPFL footprint was 0.8 ± 0.7 mm posterior (P = .012) and 5.9 ± 1.1 mm distal to the radiographic MPFC midpoint (P <.001). The radiographic point corresponding to the distal MPFL footprint was 0.8 ± 0.9 mm posterior (P = .011) and 11.1 ± 2.3 mm distal to the radiographic point of the proximal MQTFL footprint (P <.001). When using the point of intersection of the posterior cortical line and the proximal posterior condyle as a reference, 91.6% of all points correlating to the MQTFL, MPFC midpoint and MPFL, were within 10 mm in any direction from this radiographic landmark.

CONCLUSIONS

On fluoroscopic imaging, the proximal MQTFL and distal MPFL fibers had significantly different radiographic positions from the MPFC midpoint on the femur. These findings should be considered when reconstructing specific components of the MPFC.

CLINICAL RELEVANCE

As fluoroscopy is often used intraoperatively to guide graft placement, our findings may serve as a reference when differentiating the locations of the MPFL vs MQTFL on the femur for anatomic reconstruction.

Insall proximal realignment with/without tibial tubercle osteotomy for recurrent patellar instability yields acceptable medium- to long-term results but risk of osteoarthritis progression is considerable

PURPOSE

The purpose of this study was to evaluate clinical and radiological results in patients operated for recurrent patellar instability with a surgical approach consisting of Insall proximal realignment with/without tibial tubercle osteotomy (TTO).

METHODS

Patients that underwent surgery for recurrent patellar instability at one centre with a uniform technique between 2004 and 2020 were included. Eligible patients were assessed by clinical examination and the disease-specific Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0). Pre- and postoperative radiographs were analysed for patellofemoral osteoarthritis (OA) according to Iwano. Preoperative Magnetic Resonance Imaging (MRI) and radiographs were analysed for anatomical risk factors for patellar instability. Student t-test, chi-square test and ANOVA-analyses were used to investigate whether anatomical risk factors and/or patient characteristics could predict an inferior outcome.

RESULTS

Forty-six patients (47 knees) were included at a mean follow-up time of 6.6 years (SD 4.6; range 1-17). Mean BPII 2.0 score was 60.4 (SD 18.4; range 26-98), and 10.6% (n = 5) had suffered a postoperative redislocation. Progression to evident patellofemoral OA was seen in 15% of the patients (p < 0.05). The presence of pathoanatomic risk factors did not correlate with recurrent postoperative instability or inferior BPII 2.0 score at the final evaluation.

CONCLUSION

Patients treated with the current approach reported acceptable medium- to long-term results, but the risk of patellofemoral OA progression is significant. These findings add to the knowledge of expected outcomes after procedures involving Insall proximal realignment, and can guide clinical decision making for surgeons using similar methods.

LEVEL OF EVIDENCE

Level IV, case series.

Protocols of rehabilitation and return to sport, and clinical outcomes after medial patellofemoral ligament reconstruction with and without tibial tuberosity osteotomy: a systematic review

PURPOSE

No consensus exists on rehabilitation programmes after medial patellofemoral ligament reconstruction (MPFLR) with or without tibial tuberosity osteotomy (TTO). This systematic review examined the content and timeline of rehabilitation (weightbearing, range of motion [ROM] and exercise therapy) and return to sport (RTS), as well as patient-reported outcomes after MPFLR with or without TTO.

METHODS

The PubMed, Cochrane Library, Web of Sciences, CINAHL and SPORTDiscus databases were searched from inception to December 2021. Studies that reported postoperative rehabilitation programmes and patient-reported outcomes for patients aged ≥ 18 years who underwent MPFLR with or without concomitant TTO were included.

RESULTS

Eighty-five studies were included, 57 of which were case series and only one randomised controlled trial on rehabilitation programmes. Non-weightbearing was set within one week post-operatively in approximately 80% of weightbearing programmes for MPFLR without and with TTO. Joint immobilisation was set within one week post-operatively in 65.3% and 93.8% of programmes for MPFLR without and with TTO, respectively. Weightbearing and ROM (≤ 90°) restriction were within three weeks post-operatively for > 50% of the programmes. Quadriceps strengthening was the most cited exercise therapy (33 programmes), most often initiated within two weeks post-operatively. However, few other exercise programmes were cited (only nine programmes). RTS was mostly noted at six months post-operatively (35 programmes). The weighted mean Kujala score was 87.4 points.

CONCLUSION

Regardless of TTO addition to MPFLR, most studies restricted weightbearing and ROM only in the early post-operative period, with seemingly favourable clinical results. Limited information was available on post-operative exercise therapy.

A Machine Learning Algorithm Outperforms Traditional Multiple Regression to Predict Risk of Unplanned Overnight Stay Following Outpatient Medial Patellofemoral Ligament Reconstruction

Purpose

To determine whether conventional logistic regression or machine learning algorithms were more precise in identifying the risk factors for unplanned overnight admission after medial patellofemoral ligament (MPFL) reconstruction.

Methods

A retrospective review of the prospectively collected National Surgical Quality Improvement Program database was performed to identify patients who underwent outpatient MPFL reconstruction from 2006–2018. Patients admitted overnight were identified as those with length of stay of 1 or more days. Models were generated using random forest, extreme gradient boosting, adaptive boosting, or elastic net penalized logistic regression, and an additional model was produced as a weighted ensemble of the 4 final algorithms. The predictive capacity of these models was compared to that of logistic regression.

Results

Of the 1307 patients identified, 221 (16.9%) required at least one overnight stay after MPFL reconstruction. Multivariate logistic regression found the following variables to be predictors of inpatient admission: age (odds ratio [OR] = 1.03 [95% confidence interval {CI} 1.02-1.04]; P <.001), spinal anesthesia (OR = 3.42 [95% CI 1.98-6.08]; P < .001), American Society of Anesthesiologists (ASA) class 3/4 (OR = 1.96 [95% CI 1.25-3.06]; P < .001), history of chronic obstructive pulmonary disease (COPD) (OR = 6.44 [95% CI 1.58-26.17]; P = .02), and body mass index (BMI) (OR = 1.03 [95% CI 1.01-1.05]; P < .001). The ensemble model achieved the best performance based on discrimination assessed via internal validation (area under the curve = 0.722). The variables determined most important by the ensemble model were increasing BMI, increasing age, ASA class, anesthesia, smoking, hypertension, lateral release, and history of COPD.

Conclusions

An internally validated machine learning algorithm outperformed logistic regression modeling in predicting the need for unplanned overnight hospitalization after MPFL reconstruction. In this model, the most significant risk factors for admission were age, BMI, ASA class, smoking status, hypertension, lateral release, and history of COPD. This tool can be deployed to augment provider assessment to identify high-risk candidates and appropriately set postoperative expectations for patients.

Clinical Relevance

Identifying and mitigating patient risk factors to prevent adverse surgical outcomes and hospitalizations is one of our primary goals. There may be a key role for machine learning algorithms to help successfully and efficiently risk stratify patients to decrease costs, appropriately set postoperative expectations, and increase the quality of delivered care.

Editorial Commentary: A Complex Network of Bony and Soft-Tissue Stabilizers-and Overall Limb Alignment-Determines Patellofemoral Stability

Patellofemoral stability is maintained through a complex network of static and dynamic soft-tissue stabilizers, the osseous structure of the patella and trochlea, and overall limb alignment. Thus, determining the risk of recurrent patellar instability must account for as many of these factors as possible in the clinical decision-making process. The tibial tubercle-trochlear groove distance is the most common parameter used for this evaluation but may be limited because of methodologic issues and because this distance is an absolute value. Indices that incorporate other predisposing factors, including trochlear dysplasia, increase the accuracy of predicting recurrent patellar instability and can be used to generate a patient-specific treatment plan.

Derotational distal femoral osteotomy yields satisfactory clinical outcomes in pathological femoral rotation with failed medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the clinical outcomes of de-rotational distal femoral osteotomy (DDFO) in patients who underwent primary medial patellofemoral ligament reconstruction (MPFLR) failure with increased femoral anteversion along with high-grade J sign.

METHODS

Between 2011 and 2019, 14 patients underwent DDFO revision surgery due to failed MPFLR. The pre- and postoperative J sign grade, Caton-Deschamps index (CDI), tibial tuberosity-trochlear groove (TT-TG) distance, femoral anteversion angle (FAA), patellar lateral tilt angle (PLTA), MPFL graft laxity, and patient-reported outcomes (Kujala, Lysholm, Tegner, and International Knee Documentation Committee (IKDC) subjective scores) were collected. The anterior-posterior and proximal-distal distances between the actual point and the Schöttle point were also calculated.

RESULTS

Fourteen patients underwent MPFLR revision by DDFO combined with MPFLR. The mean PLTA improved from 40.7° ± 11.9° to 20.5° ± 8.7° (P < 0.001). The mean FAA significantly decreased from 42.7° ± 12.0° to 14.1° ± 5.2° (P < 0.001). The mean patellar laxity index (PLI) decreased from 82.4% preoperatively to 15.1% postoperatively (P < 0.001). None of these patients experienced subluxation or re-dislocation during follow-up of 29.7 ± 5.0 months after revision surgery. Meanwhile, the Tegner score at the last follow-up ranged from 3 to 6, with a median of 5. The Kujala, Lysholm, and IKDC subjective scores showed significant improvements, from a mean of 51.0 ± 6.8 preoperatively to 75.4 ± 5.1 postoperatively (P < 0.001), 49.2 ± 7.9 to 75.2 ± 7.2 (P < 0.001), and 42.9 ± 6.2 to 76.8 ± 6.0 (P < 0.001), respectively. The proportion of patients with a high-grade J sign was significantly lower postoperatively than preoperatively (100% vs. 14%). Four out of 14 patients (29%) showed femoral tunnel mal-positioning.

CONCLUSION

MPFLR revision by DDFO combined with MPFLR achieved favorable clinical outcomes in patients with increased femoral anteversion along with high-grade J sign.

LEVEL OF EVIDENCE

IV.

Lateral Patellar Dislocation: A Critical Review and Update of Evidence-Based Rehabilitation Practice Guidelines and Expected Outcomes

»

Nonoperative treatment of a lateral patellar dislocation produces favorable functional results, but as high as 35% of individuals experience recurrent dislocations.

»

Medial patellofemoral ligament reconstruction is an effective treatment to prevent recurrent dislocations and yield excellent outcomes with a high rate of return to sport.

»

Both nonoperative and postoperative rehabilitation should center on resolving pain and edema, restoring motion, and incorporating isolated and multijoint progressive strengthening exercises targeting the hip and knee.

»

Prior to return to sports, both functional and isolated knee strength measurements should be used to determine leg symmetry strength and to utilize patient-reported outcome measures to assess the patient's perceived physical abilities and patellofemoral joint stability.

Central Transpatellar Tendon Portal Is Safe When Used for Anterior Cruciate Ligament Reconstruction

Central transpatellar tendon portal (CTP) was suggested first for complex meniscal lesion and subsequently for a better femoral footprint view during reconstruction of anterior cruciate ligament (ACL). A comprehensive evaluation of possible consequences of using the CTP performing an ACL reconstruction does not exist. Our hypothesis was that the use of CTP for ACL reconstruction does not lead to a higher rate of complications or clinically evident radiological abnormalities. In total, 141 patients were prospectively evaluated, 69 underwent ACL reconstruction using a standard high medial portal as view portal, and 72 where a CTP was used. Clinical evaluation, Kujala's score, patellar height, and magnetic resonance (MR) abnormalities were evaluated up to 1-year follow-up. Clinical complications were reported in 16 cases with no statistically significant differences between the two groups. The group 2 had significantly more MR abnormalities (p = 0.048), but the differences in MR alterations do not have any clinical repercussion even in a sports-active population. No differences were found between the groups in Kujala's score, time to return to work, and sport or patellar height. The overall mean preoperative Caton-Deschamps Index decreased significantly (p = 0.034) postoperatively. Postoperative patellar height seems to slightly decrease after ACL reconstruction regardless of the kind of the portals used intraoperatively and the initial patellar height. Nevertheless, this change in patellar height does not influence the postoperative outcome. CTP used for ACL reconstruction does not lead to significative major clinical complications.

Femoral tunnel malposition is the most common indication for revision medial patellofemoral ligament reconstruction with promising early outcomes following revision reconstruction: a systematic review

PURPOSE

The purpose of this study was to identify the causes of failure of previous medial patellofemoral ligament reconstruction (MPFL-R), and to furthermore report the surgical techniques available for MPFL revision surgery.

METHODS

Four databases [PubMed, Ovid (MEDLINE), Cochrane Database, and EMBASE] were searched until September 29, 2020 for human studies pertaining to revision MPFL. Two reviewers screened the literature independently and in duplicate. Methodological quality of the included studies was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria, or the CAse REport guidelines (CARE), where appropriate.

RESULTS

Fourteen studies (one level II, one level III, two level IV, ten level V) were identified. This search resulted in a total of 76 patients with a mean age (range) of 22 (14-39) years. The patients were 75% female with a mean (range) time to revision of 24.1 (1-60) months and mean (range) follow-up of 36.2 (2-48) months. The most common indication for revision surgery was malpositioning of the femoral tunnel (38.1%), unaddressed trochlear dysplasia (18.4%), patellar fracture (11.8%). Femoral tunnel malposition was typically treated via revision MPFL-R with quadriceps tendon or semitendinosus autograft and may retain the primary graft if fixation points were altered. Unaddressed trochlear dysplasia was treated with deepening trochleoplasty with or without revision MPFL-R, and patella fracture according to the nature of the fracture pattern and bone quality. Though generally, outcomes in the revision scenario across all indications were inferior to those post-primary procedure, overall, revision patients demonstrated positive improvements in pain and instability symptoms. Transverse patella fractures treated with debridement and filling with demineralized bone matrix if required with further fixation according to the fracture pattern.

CONCLUSION

The most common causes of MPFL failure in literature published to date, in order of decreasing frequency, are: malposition of the femoral tunnel, unaddressed trochlear dysplasia, and patellar fracture. Although surgical techniques of revision MPFL-R to manage these failures were varied, promising outcomes have been reported to date. Larger prospective comparative studies would be useful to clarify optimal surgical management of MPFL-R failure at long-term follow-up.

LEVEL OF EVIDENCE

IV.

Arthroscopic Patellofemoral Measurements Can Reliably Assess Patellar Instability

PURPOSE

To arthroscopically describe patellar position based on lateralization, tilt, and engagement, and compare measurements in normal, medial patellofemoral complex-(MPFC) deficient, and MPFC-reconstructed knees.

METHODS

In 10 cadaveric knees, arthroscopic patellar position was assessed by performing digital measurements on arthroscopic images obtained through a standard anterolateral portal. Lateralization was measured as millimeters overhang of the patella past the lateral edge of the lateral femoral condyle, viewing from the lateral gutter. Patellar tilt was calculated as the difference in medial and lateral distances from the patella to the trochlea, viewing from the sunrise view. Patellotrochlear distance was measured as the anteroposterior distance between the central trochlear groove and patella on the sunrise view. Measurements were obtained at 10° intervals of knee flexion from 0° to 90°, in intact knees (group 1), after arthroscopically transecting the MPFC fibers (group 2), and after MPFC reconstruction (group 3). Optimal cutoff values were identified to distinguish between intact versus MPFC-deficient states.

RESULTS

When compared to group 1, group 2 demonstrated increased patellar lateralization by 22.5% at 0°-40° knee flexion (P = .006), which corrected to baseline in group 3 (P = .006). Patellar tilt measurements demonstrated no differences between groups. Patellotrochlear distance increased by 21.0% after MPFC transection (P = .031) at 0°-40° knee flexion, with correction to baseline after MPFC reconstruction (P = .031). More than 7 mm of lateral overhang at 20°-30° flexion and >6 mm of patellotrochlear distance at 10°-20° flexion were found to indicate MPFC deficiency.

CONCLUSIONS

Utilizing standardized arthroscopic views, we identified significant increases in patellar lateralization and patellotrochlear distance in early knee flexion angles after MPFC transection, and these changes normalized after MPFC reconstruction.

CLINICAL RELEVANCE

Arthroscopic assessments of patellar position may be useful in evaluating patellofemoral stability during patellar stabilization surgery.

Are Patellofemoral Ligaments and Retinacula Distinct Structures of the Knee Joint? An Anatomic, Histological and Magnetic Resonance Imaging Study

There is disagreement regarding the description of the patellofemoral ligaments (PFLs), considered by some authors as capsular thickening and by others as independent ligaments. It was hypothesised that the PFLs and retinacula are structures with different histological features. The aim of this study was to describe the stabilising structures of the patella in detail and to determine if the PFLs and retinacula are different and separable structures from a macroscopic, microscopic and imaging viewpoint. An anatomical study was performed on eight knees from five cadavers (mean age, 56.2 years; range, 35–63 years), and a histological study was conducted on specimens from nine patients having a mean age of 65 years (range 35–84 years) who had undergone surgical knee procedures. The imaging study was based on 100 MRIs (96 patients). The mean age was 46 years (range 16–88), and the study analysed the capsular-ligamentous structures. In the medial compartment, the layers and structures were as follows: superficial layer, medial retinaculum; intermediate layer, Medial Collateral Ligament (MCL), Posterior Oblique Ligament (POL) and Medial Patellofemoral Ligament (MPFL); deep layer, deep part of the MCL and joint capsule. In the lateral compartment, the layers and structures were the following: superficial layer, lateral retinaculum; intermediate layer, Lateral Collateral Ligament (LCL) and Lateral Patellofemoral Ligament (LPFL); deep layer, joint capsule. All of the knees examined presented a clearly distinguishable MPFL and LPFL separable from the capsular layer. Histological study: there was a higher density of nerve fibres in retinacula compared to ligaments (p = 0.0034) and a higher content of elastic fibres in retinacula (p < 0.0005). In imaging, there was no difference between medial and lateral retinaculum thickness (p > 0.05). In conclusion, both the lateral and medial compartment can be described using the three-layer scheme. PFLs and retinacula are separate structures both macroscopically and according to imaging analysis. The retinacula respond to their specific function with a higher nerve fibre content and higher number of elastic fibres compared to the ligaments.

The novel dynamic MPFL-reconstruction technique: cheaper and better?

PURPOSE

Reconstruction of the medial patellofemoral ligament (MPFL) is an established procedure to restore patellar stability. Aim of this study is to evaluate the results of a dynamic MPFL reconstruction technique in a large university hospital setting.

METHODS

Two hundred and thirteen consecutive patients with 221 knees were surgically treated for recurrent lateral patellar dislocation. All patients obtained dynamic reconstruction of the MPFL with detachment of the gracilis tendon at the pes anserinus while maintaining the proximal origin at the gracilis muscle. Patellar fixation was performed by oblique transpatellar tunnel transfer. Follow-up data including Kujala and BANFF score, pain level as well as recurrent patella instability were collected at a minimum follow-up of 2 years.

RESULTS

Follow-up could be obtained from 158 patients (71%). The mean follow-up time was 5.4 years. Mean pain level was 1.9 ± 2.0 on the VAS. Mean Kujala score was 78.4 ± 15.5. Mean BANFF score was 62.4 ± 22.3. MPFL-reconstructions that were performed by surgeons with a routine of more than ten procedures had a significantly shorter surgical time 52.3 ± 17.6 min. Male patients yielded higher satisfaction rates and better clinical scores compared to females. Complications occurred in 27.2% of procedures, 20.9% requiring revision surgery of which were 9.5% related to recurrent patellar instability. 78% of all patients indicated they would undergo the procedure again.

CONCLUSION

Dynamic MPFL reconstruction presents a reproducible procedure with increased complication rates, inferior to the results of static reconstruction described in the literature. Despite, it appears to be an efficient procedure to restore patellar stability in a large university hospital setting, without the necessity for intraoperative fluoroscopy.

TRIAL REGISTRATION

The study was registered in ClinicalTrials.gov with the registration number NCT04438109 on June 18th 2020.

Rehabilitation and Return to Sport After Medial Patellofemoral Complex Reconstruction

The medial patellofemoral complex (MPFC) consists of the medial patellofemoral ligament and medial quadriceps tendon femoral ligament, which play a critical role stabilizing the patella against lateral translation. After a patellar dislocation, athletes with recurrent dislocations have functional limitations that may limit their return to their prior level of competition, requiring surgical reconstruction. Although ample literature exists delineating return-to-play (RTP) considerations after anterior cruciate ligament reconstruction, there is a paucity of evidence specific to MPFC reconstruction. Athletes aiming to return to sport after MPFC reconstruction require the same methodical treatment approach to ensure safe RTP. A criterion-based periodical assessment of progress that measures range of motion, strength, neuromuscular control, balance, agility, and power are pivotal components of rehabilitating this population. A combination of objective and subjective criteria should be assessed when determining an individual’s readiness for sports-specific activities. A battery of functional tests, including quadriceps strength testing, single-limb hop testing, lateral step-down test, the lateral leap and catch test, the Y-balance test, and the depth jump should be considered when evaluating the athlete for readiness for sport, incorporating specific understanding of the biomechanics of the patellofemoral joint. We discuss the considerations for return-to-sport rehabilitation and testing after MPFC reconstruction, to provide clinicians working with an athletic population a framework to adequately prepare their athletes for safe return to sport.

Relationship between Anatomical Risk Factors, Articular Cartilage Lesions, and Patient Outcomes Following Medial Patellofemoral Ligament Reconstruction

OBJECTIVE

The purpose of this study was (1) to determine which risk factors for patellar instability were associated with the presence of patellofemoral cartilage lesions and (2) to determine how cartilage lesion presence, size, and grade affect postoperative disease-specific quality of life.

DESIGN

Preoperative, intraoperative, and postoperative demographic, anthropometric (body mass index, Beighton score, hip rotation), radiographic (crossover sign, trochlear bump), cartilage lesion morphology (presence, size, location, grade), and outcomes data (Banff Patella Instability Instrument 2.0 [BPII 2.0]) were prospectively collected from patients undergoing isolated medial patellofemoral ligament reconstruction. For all knees (n = 264), single and multivariable logistic regression was used to determine if any patellar instability risk factors affected the odds of having a cartilage lesion. In patients with unilateral symptoms (n = 121), single variable linear regression was used to determine if the presence, size, or ICRS (International Cartilage Regeneration & Joint Preservation Society) grade of cartilage lesions could predict the 12 or 24+ month postoperative BPII 2.0 score.

RESULTS

A total of 84.5% of knees had patellofemoral cartilage lesions (88.3% involved the distal-medial patella). Trochlear dysplasia (high grade: odds ratio = 15.7, P < 0.001; low grade: odds ratio = 2.9, P = 0.015) was associated with the presence of a cartilage lesion. The presence, size, and grade of cartilage lesions were not associated with 12 or 24+ month postoperative BPII 2.0 scores.

CONCLUSIONS

Trochlear dysplasia was a risk factor for the development of patellofemoral cartilage lesions in this patient population. Cartilage lesions most commonly involve the distal-medial patella. There was no significant relationship between patellofemoral cartilage lesion presence, size, or grade and postoperative BPII 2.0 scores in short-term follow-up.

Combined MPFL reconstruction and tibial tubercle osteotomy for patellar instability: A retrospective review of 23 patients

The primary objective of this retrospective study is to compare patient outcomes following a combined approach (MPFL reconstruction and TTT) to outcomes reported in the literature by patients who required either only an isolated TTT procedure to treat pathologic lateral patellar instability or isolated MPFL reconstruction to treat patellar dislocation due to MPFL insufficiency. Twenty-three patients (74%) were available for follow-up and are included in our analysis. MPFL reconstruction combined with TTT has a high rate of success for patients presenting with patellar instability and extensor mechanism mal-alignment. The risk of recurrence with this technique was low (4.3%).

Anatomic medial patellofemoral ligament (MPFL) reconstruction with and without tibial tuberosity osteotomy for objective patellar instability

PURPOSE

The aim of this study was to evaluate the clinical outcomes of patients treated with anatomic medial patellofemoral ligament (MPFL) reconstruction with and without tibial tuberosity osteotomy (TTO). Correlations between patient's age, gender, pre-injury physical activity and the achieved results were investigated as secondary endpoints.

METHODS

An observational retrospective study with prospective collected data was performed. Inclusion criteria were: treatment with anatomic MPFL reconstruction with gracilis tendon according to Schӧttle's technique performed between 2011 and 2017; associated TTO as unique accessory procedure; skeletal joint maturity; a minimum follow-up of 12 months after surgery. Clinical outcomes were assessed with the Kujala, Lysholm and Tegner scores.

RESULTS

Forty patients (42 knees) were included, 64% of them underwent TTO. The Kujala score significantly improved from 47.4 ± 17.6 preoperatively to 89.4 ± 13.6 postoperatively (p < 0.01). The average Lysholm score was 45.6 ± 20.5 preoperatively: it showed a significant increase to 89.8 ± 12.8 postoperatively (p < 0.01). Pre-injury mean Tegner was 5.9 ± 1.8, while it dropped to 3.0 ± 1.6 after injury. After surgery, Tegner resulted 4.9 ± 1.6. Forty-three percent of patients regained the pre-injury sport activity level. Redislocation rate was 2.4%.

CONCLUSION

Anatomic MPFL reconstruction allows excellent patellar stability recovery, knee functionality improvement, return to Activities of Daily Living and a low redislocation rate. Better results were achieved in younger (under 30 years old) and higher sports activity-level subjects. The TTO association provided clinical results comparable to isolated MPFL reconstructions, suggesting that the two procedures can be safely accomplished together without affecting the positive outcomes.

LEVEL OF EVIDENCE

Level IV.

Age at surgery is correlated with pain scores following trochlear osteotomy in lateral patellar instability: a cross-sectional study of 113 cases

Background

A trochlear osteotomy aims to restore patellar stability in patients with recurrent patellar instability and trochlear dysplasia. The age of patients at time of surgery could be a relevant factor which influences outcome. We hypothesized that lower age at time of surgery is associated with better patient-reported outcomes.

Methods

A retrospective study was conducted on patients with patellar instability and trochlear dysplasia. Patients were contacted by phone for informed consent and were then asked to complete online patient-reported outcome measurements (PROMs). The PROMs consisted of the Kujala Knee Score (KKS) (Kujala et al., Arthroscopy 9(2):159-63, 1993; Kievit et al. Knee Surg Sports Traumatol Arthrosc. 21(11):2647-53, 2013), the Short Form 36-item health survey (SF-36v1) (Ware, Med Care 73-83, 1992; Aaronson et al., J Clin Epidemiol. 51(11):1055-68, 1998), and visual analog scale (VAS) scoring pain, instability, disability, and satisfaction on a 0–100 scale. Multivariable linear regression models were used to study the effect of age on the PROM scores.

Results

For this study, 125 surgical procedures in 113 patients were included. Mean VAS pain at rest was 19 and at activity 38; mean Kujala score was 73. Multivariable regression analysis revealed that age at the time of surgery was correlated with VAS pain at rest, with a 0.95 increase of VAS score (scale 0–100) for every year of age. Recurrence of instability was observed in 13 (10%) knees.

Conclusion

In this cross-sectional study, pain scores of 113 patients who have undergone a lateral facet elevating trochlear osteotomy for patellar instability were reported. Age at time of surgery was correlated with an increased pain score at rest with an average of 9.5 points (scale 0–100) for every 10 years of age. Age at time of surgery was not correlated with overall satisfaction.

Good results are reported at 60-month follow-up after medial patello-femoral ligament reconstruction with fascia lata allograft for recurrent patellar dislocation

PURPOSE

The aim of this study was to evaluate the efficacy of a new minimally invasive surgical technique for the reconstruction of the medial patellofemoral ligament (MPFL) with fascia lata allograft at 60-month minimum follow-up.

METHODS

Nineteen consecutive patients with chronic recurrent patellar dislocation were treated with MPFL reconstruction (53% isolate procedure, 47% in combination with other treatments). Seventeen patients (11 males/6 females) were available at 60-month follow-up and were clinically evaluated with validated scores. New episodes of patellar dislocation were considered failures. Radiographic and CT scan evaluation were executed preoperatively and at 60-month follow-up.

RESULTS

All clinical scores improved from preoperative assessment to 24-month and 60-month follow-up (p < 0.001). Kujala score increased from 61.2 ± 18.1 to 86.7 ± 8.7 and 82.1 ± 10.2; KOOS increased from 54.5 ± 19 to 86.8 ± 9.6 and 84.3 ± 7.6; VAS for pain decreased from 5.1 ± 2.2 to 2.4 ± 1.5 and 1.7 ± 1.2; Tegner score increased from 3 [2-4] to 5 [3-8] and 5 [3-9], respectively. Objective IKDC improved too. No significant improvements between the 24-month and 60-month follow-up evaluations were recorded. Anterior knee pain was reported in two patients (12%). Treatment failure, a new episode of patellar dislocation 25 months after the surgery, was observed in one patient (6%). Radiographic OA changes were not statistically significant between preop and 60-month follow-up. Tuberosity-troclear groove (TT-TG) distance and the patellar tilt angle were subjected to significant changes due to MPFL reconstruction and associated procedures.

CONCLUSION

MPFL reconstruction with fascia lata allograft, alone or combined with other procedures, is a reliable treatment option for recurrent patellar dislocation with a success rate of 94% and without cartilage deterioration at 60-month follow-up.

LEVEL OF EVIDENCE

IV.

Isolated reconstruction of medial patellofemoral ligament with an elastic femoral fixation leads to excellent clinical results

PURPOSE

The primary objective was to compare the functional outcomes after an isolated MPFL reconstruction using either a quasi-anatomical technique (group A) or an anatomical MPFL reconstruction (group B). The secondary objectives were to compare the rates of redislocation, range-of-motion and subjective patellar instability (Smillie test).

METHODS

A multicenter longitudinal prospective comparative study was performed. Group A had 29 patients and 28 were included in Group B. Patients with trochlear dysplasia types C and D and patients who had undergone a trochleoplasty, a distal realignment or patella distalization concurrently with MPFL reconstruction were excluded. The main evaluation criterion was the Kujala functional score.

RESULTS

The mean postoperative Kujala was 90.4 (89.4 in group A and 92.1 in group B). Upon comparing the mean difference between pre- and post-operative values, no differences were detected between the two groups (n.s).

CONCLUSIONS

Isolated quasi-anatomical MPFL reconstruction using a gracilis tendon autograft for recurrent patellar dislocation provides outcomes as good as the isolated anatomical MPFL reconstruction in patients with no trochlear dysplasia up to those with trochlear dysplasia type A and B at the 2-5 years follow-up.

LEVEL OF EVIDENCE

Level IV.

Complex patellofemoral reconstruction leads to improved physical and sexual activity in female patients suffering from chronic patellofemoral instability

PURPOSE

To analyze postoperative physical and sexual activity as well as Quality of Life (QoL) after complex patellofemoral reconstructions in female patients suffering from chronic patellofemoral instability (PFI).

METHODS

Female patients aged > 18 years undergoing complex patellofemoral reconstruction for chronic PFI were included. Complex patellofemoral reconstruction was defined as medial patellofemoral ligament reconstruction (MPFL-R) combined with at least one major bony procedure (distal femoral osteotomy, high tibial osteotomy, and trochleoplasty). Outcome was evaluated retrospectively after a minimum follow-up of 12 months using Tegner activity scale, Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0), EuroQol-5D-3L (EQ-5D-3L), EuroQol Visual analog scale (EQ-VAS), and a questionnaire about sexual activity.

RESULTS

A total of 34 females (mean age, 26 ± 5 years) with a mean follow-up of 45 ± 16 months were included. Seventy-seven percent had one major bony correction + MPFL-R and 24% had at least two major bony corrections + MPFL-R. The re-dislocation rate was 6%. Median Tegner activity scale improved from 3 (range 0-10) to 4 (range 2-6) (n.s.) and an improved activity level was observed in 49% of subjects. QoL scores showed an EQ-5D-3L Index Value of 0.89 ± 0.15, EQ-VAS of 80.3 ± 11.4, and BPII of 68.3 ± 19.1. Thirty-four percent of patients reported restrictions of sexual activities due to PFI preoperatively with an improved sexual function observed in 60% postoperatively due to less pain, improved mobility, and less apprehension. Postoperative return to sexual activity was 91%, whereof 19% reported current restrictions of sexual function because of pain and/or limited range of motion.

CONCLUSION

Despite the complexity and invasiveness of complex patellofemoral reconstruction, combined bony procedures and MPFL-R resulted in a low redislocation rate, improved physical activity and QoL comparable to values reported after isolated MPFL-R. Furthermore, sexual activity was improved in 60% of females with preoperative restrictions.

LEVEL OF EVIDENCE

IV.

Anatomical Medial Patellofemoral Ligament Reconstruction for Recurrent Patella Dislocation: Two-Strand Grafts versus Four-Strand Grafts

The purpose of this study was to describe two anatomical medial patellofemoral ligament (MPFL) reconstruction methods: reconstruction with two-strand grafts and reconstruction with four-strand grafts and to evaluate the clinical and radiological results. From January 2010 to January 2013, patients who sustained recurrent patella dislocation and met inclusion criteria were included in the study and divided into two groups randomly to undergo MPFL reconstruction either by two-strand grafts (T group) or four-strand grafts (F group). Patients were followed up 1 month, 1 year, 2 years, and 3 years postoperatively. The apprehension test was applied to test patella stability. The Kujala score, Lysholm score, and Crosby-Insall grading were used to evaluate the function of the affected knee. The patellar congruence and patellar tilt angle were used to measure the morphology of the patellofemoral joint. In addition, patients' subjective assessments and complications were recorded. Thirty-eight patients in T group and 38 patients in F group were followed for at least 36 months. The apprehension test was positive in all patients preoperatively but was negative at follow-up. The Kujala score, Lysholm score, patellar congruence angle, and the patellar tilt angle of patients in both groups improved significantly at 36-month follow-up when compared with those assessed preoperatively. However, patients in the F group achieved better clinical results in terms of Kujala score, patellar congruence angle, patellar tilt angle, and Crosby-Insall grading when compared with those in the T group 3 years after the operation. Most patients (92% of patients in the T group and 97% of patients in the F group) were satisfied with the surgery. The anatomical MPFL reconstruction with two-strand grafts or four-strand grafts were both safe techniques for recurrent patella dislocation with satisfactory clinical outcomes. The anatomical fixation with four-strand grafts achieved better clinical and radiographic results in the follow-up, which may be a better reconstruction method.

Development of an innovative measurement method for patellar tracking disorder

In this study, we investigated whether the measurement of patellar tracking can be used as a diagnostic parameter of patellofemoral joint disease. Patellar tracking is defined as the movement of the patella in relation to the femorotibial joint within the full range of flexion and extension of the knee joint. The PubMed, EMBASE, Medline, PsychINFO, and AMED databases were used to find relevant articles. Analyzed were the patellar tracking coordinate system and the measurement objects, precision, methods used in those studies, as well as the results obtained. Origin points for coordinate systems varied across the studies. The research object and methods of patellar tracking varied in the studies. Most studies focused on a static description of the internal and external displacement and the internal and external inclination. The in vivo, noninvasive, and six degrees of freedom evaluation of patellar tracking reflect patellar motion more comprehensively, though each of these methods does so in different ways. Dynamic and quantitative evaluation of patellar tracking is still lacking in clinical work. Accurate and quantitative patellar tracking measurement could provide clinicians with a comprehensive evaluation of the stability of the knee joint.

Midterm Results after Implant-Free Patellar Fixation Technique for Medial Patellofemoral Ligament Reconstruction

Problems and complications concerning the patellar fixation in medial patellofemoral ligament reconstruction (MPFLR) have been reported. The purpose of this retrospective study was to systematically analyze the surgical technique for MPFLR with a V: -shaped patellar bonetunnel for implant-free fixation of an autologous gracilis tendon, allowing early functional rehabilitation, regarding restoration of the patellofemoral stability, patient satisfaction, return to sports, and technique-specific complications. In 2010, 128 cases of consecutive isolated MPFLR were performed. All these cases were included. After a minimum follow-up of 3 years, 104 cases were retrospectively analyzed (follow-up: 81.3%) with regard to redislocation, subjective functional outcome (Tegner's score and sports level compared with preoperative level), patient satisfaction, revision surgery, and technique-specific complications. After a follow-up of 45.7 ± 3.2 months, 101 of 104 cases (97.1%) showed no redislocation. Mean Tegner's score was 5.1 ± 1.8 (range, 2-9). A total of 61.5% patients reported about a higher sports level compared with their preoperative level. The patient satisfaction was high with 94.2%. In two cases (1.9%), technique-specific problems occurred as the bone bridge of the V: -shaped tunnel was insufficient due to a malpositioning of the aiming device. No further technique-specific problems occurred and no revision surgery was necessary during the observational period. The presented surgical technique is safe and it reliably restores the patellofemoral stability, with a low rate of redislocations, an excellent subjective functional outcome, and a high-patient-reported satisfaction. No major technique-specific complications occurred.

Tibial Tubercle-Midepicondyle Distance Can Be a Better Index to Predict the Outcome of Medial Patellofemoral Ligament Reconstruction Than Tibial Tubercle-Trochlear Groove Distance

Purpose

To compare the clinical utility of tibial tubercle-midepicondyle (TT-ME) and tibial tubercle-trochlear groove (TT-TG) distances in predicting the risk for recurrent instability after isolated MPFL reconstruction.

Methods

A consecutive series of patients with recurrent patellar dislocation who underwent isolated MPFL reconstruction made up the study population. The patients were followed for a minimum of 2 years. In assessment of surgical outcome, the patient was deemed to exhibit “postoperative recurrent patellar instability” when ≥1 of the following 3 conditions was identified: redislocation, positive apprehension sign, and positive J-sign (manifestation of abnormal patellar tracking). As for radiological parameters for position of the tibial tubercle, TT-ME distance (transverse distance between the tibial tubercle and midpoint of the transepicondylar line) and TT-TG distance were measured on axial computed tomography images. The clinical utility as a factor to predict the outcome of MPFL reconstruction was compared between the 2 distances using receiver operating characteristic (ROC) analysis. In addition, various radiological indices potentially influencing the surgical outcome were subjected to multivariable logistic regression analysis.

Results

We examined 38 knees in 38 patients with a mean age at surgery of 17.6 years. Postoperative recurrent patellar instability was encountered in 8 of the 38 knees. The ROC curve analysis showed the TT-ME distance to be a significantly better indicator in predicting surgical outcome than the TT-TG distance (P = .001). The univariate analysis for radiological factors demonstrated that the TT-ME distance was significantly associated with postoperative recurrent patellar instability (odds ratio 1.42, P = .012) whereas all other factors including the TT-TG distance did not correlate with recurrent instability. The multivariable logistic regression analysis revealed that only the TT-ME distance was significantly associated with recurrent instability (P = .035).

Conclusions

Analysis of our patient population undergoing isolated MPFL reconstruction showed that the TT-ME distance was a significantly better indicator than the TT-TG distance to predict the risk for recurrent instability after isolated MPFL reconstruction performed for patellar instability.

Level of Evidence

Level IV, therapeutic case series.

Recurrent Patellar Dislocations Without Untreated Predisposing Factors: Medial Patellofemoral Ligament Reconstruction Versus Other Medial Soft-Tissue Surgical Techniques-A Meta-analysis

PURPOSE

To provide a direct comparison between medial patellofemoral ligament (MPFL) reconstruction and the other medial patellofemoral soft-tissue surgeries in the restoration of the medial patellar restraint after lateral patellar dislocations in the absence of untreated predisposing factors such as high grade trochlear dysplasia, knee malalignment, patella alta or high tibial tubercle-trochlear groove distance.

METHODS

PubMed, Cochrane-library, Web of Science, and gray literature databases were searched to find all the relevant records. Study selection, data extraction, and risk of bias assessment were performed following the Cochrane and Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Different techniques to treat lateral patellar dislocation in the absence of untreated predisposing factors were compared in terms of redislocation and complication rates, Kujala, Lysholm, International Knee Documentation Committee, and Tegner scores at the short-term (3 years) and long-term (>3 years) follow-up through meta-analyses.

RESULTS

Six studies involving 319 knees were included in the meta-analysis. The analyses of redislocation (0.7% vs 2.9%) and minor complication rates (12% vs 9%) showed no significant differences between MPFL reconstruction and other medial soft-tissue surgeries. Significant differences favoring MPFL reconstruction were documented in Kujala and Lysholm scores at short-term (8.6, P< .001; 10.9, P < .001) and long-term follow-ups (6.3, P = .02; 13.5, P < .001). No significant differences were found in the analyses of International Knee Documentation Committee (P = .10) and Tegner scores (P = .19). Level of evidence was low or very low.

CONCLUSIONS

MPFL reconstruction and medial patellofemoral soft-tissue surgery procedures were both effective in restoring the medial restraining forces preventing redislocation, but MPFL reconstruction provided better functional outcomes both at short-term and long-term follow-up. Thus, besides the treatment of predisposing factors, MPFL reconstruction seems to be, based on the results of this meta-analysis, a suitable strategy to restore the medial restraining function in the treatment of recurrent LPD.

LEVEL OF EVIDENCE

Level III (meta-analysis of randomized and nonrandomized comparative trials).

MPFL reconstruction: indications and results

BACKGROUND AND AIM

The medial patellofemoral ligament (MPFL) is the most important structure commonly injured during lateral patellar dislocation and its rupture accounts for 3% of total knee injuries. MPFL reconstruction (MPFLR) is a reliable procedure with good results but variable rates of recurrent instability. The aim of this study is to underline the proper indications for the MPFLR reconstruction and to explain all the pearls and pitfalls regarding the MPFLR both in our experience and found in the latest literature.

METHODS

A comprehensive search in the latest literature using various combinations of the keywords MPFL, MPFLR, dislocation, treatment was performed. The following data were extracted: diagnosis methods, indications and contraindications for isolated MPFLR, type of management, recurrence of instability, outcomes and complications.

RESULTS

History of multiple patellar dislocations is the most relevant indication for ligament reconstruction especially after a failed course of conservative treatment in presence of persistent patello-femoral instability. Gold standard technique for MPFLR has not been clearly defined yet.

CONCLUSIONS

There is still poor literature about outcome comparisons, therefore it is challenging to decide which technique is the most appropriate as surgical procedures are continuously developing. The ideal candidates for MPFLR have to be decided after a throughout evaluation and careful planning and, with nowadays knowledge, it is possible to put indication for a reconstruction exposing the patient to minimal risks.

Does surgical treatment produce better outcomes than conservative treatment for acute primary patellar dislocations? A meta-analysis of 10 randomized controlled trials

Purpose

The objective of this study was to conduct the latest meta-analysis of randomized controlled trials (RCTs) that compare clinical results between surgery and conservative therapy of acute primary patellar dislocation (APPD), focusing on medial patellofemoral ligament (MPFL) reconstruction.

Methods

We performed a literature search in Embase, The Cochrane Library, PubMed, and Medline to identify RCTs comparing APPD surgical treatment with conservative treatment from the establishment of each database to January 2019. The methodological quality of each RCT was assessed independently by the two authors through the Cochrane Collaboration’s “Risk of Bias” tool. Mean differences of continuous variables and risk ratios of dichotomous variables were computed for the pooled data analyses. The I² statistic and the χ² test were used to evaluate heterogeneity, with the significance level set at I² > 50% or P < 0.10.

Results

Ten RCTs with a sum of 569 patients (297 receiving surgical treatment and 263 receiving conservative treatment) met the inclusion criteria for meta-analysis. Pooled data analysis showed no statistical difference in the field of subluxation rate, Kujala score, patient satisfaction, and frequency of reoperation between the two groups. Tegner activity score and recurrent dislocation rate in the conservative group were significantly higher than those in the surgically treated group.

Conclusions

Conservative treatment may produce better outcomes than surgery for APPD in consideration of Tegner activity score. However, in view of limited research available, the interpretation of the discoveries should be cautious. More convincing evidence is required to confirm the effect of MPFL reconstruction.

Subjective Knee Function and Risk of Failure Are Equivalent for Men and Women at 5 Years After Meniscus Repair

PURPOSE

To determine whether subjective knee function or risk of repair failure differ between men and women at mean 5 years following meniscal repair with or without concomitant anterior cruciate ligament reconstruction.

METHODS

A total of 235 patients (97 women, 138 men; mean age, 29.1 years; standard deviation, 11.3) were assessed for meniscus repair failure and postoperative knee function at mean 5.8 years follow-up. Knee symptoms were assessed with International Knee Documentation Committee Subjective (IKDC-S) scores. Postoperative activity scores were assessed with Marx activity score. Independent effects of patient age and activity level on meniscus failure risk and patient-reported outcomes were determined by multivariate analysis with adjustment for age, body mass index, anterior cruciate ligament status, tear pattern, and number of implants used at the time of surgery.

RESULTS

Failures occurred in 18.9% of men and 21.0% of women with no difference in mean time to failure (P = .75) or risk of failure for men vs women (P = .57) in the univariate analysis. Male sex was not an independent risk factor for failure after adjustment for patient age, body mass index, concomitant anterior cruciate ligament status, tear pattern, or number of implants used (P = .16). Marx activity scores at follow-up were higher among men in multivariate analysis (P = .009). Men and women had similar IKDC-S scores at follow-up in the unadjusted (P = .25) and multivariate analyses (P = .21).

CONCLUSIONS

Following meniscus repair, both sexes report similar subjective knee function, though men have higher self-reported activity scores. Meniscus repair failure risk does not differ between men or women at mid-term follow up.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Self-reported and performance-based outcomes following medial patellofemoral ligament reconstruction indicate successful improvements in knee stability after surgery despite remaining limitations in knee function

PURPOSE

To evaluate short- to midterm outcomes of medial patellofemoral ligament reconstruction (MPFL) using patient-reported outcome measures and functional testing.

METHODS

Twenty-four patients were examined regarding knee function after MPFL reconstruction, with a mean follow-up time of 45.3 ± 18.4 months since surgery. Knee function was evaluated using the Tegner score, VAS, the knee injury and osteoarthritis outcome score (KOOS), the Lysholm score, SF-36 and EQ-5D-3L as well as functional scores. A group of uninjured persons of the same age and same gender composition was used for comparison.

RESULTS

Eight (40%) patients managed to return to their pre-injury activity level. Five (25%) patients stated that they had experienced further patella dislocations after surgery but only two (10%) had sought medical help. Patients showed significantly poorer results in all PROMs compared to controls. The results obtained with SF-36 showed significant differences in physical health between the groups, but not in mental health. The functional performance test results showed overall poorer results for the patients versus controls: 11.5 sets for the square jump (6.7-15.7) versus 21 sets (18-26), 11.5 sets for the step-down test (6.5-15) versus 22 sets (18-26), and 77 cm for the single-leg hop for distance (32.2-110.5) versus 126 cm (115-37); all (P < 0.005).

CONCLUSIONS

After MPFL reconstruction, patients do not regain normal knee function, as measured by PROMs and functional tests, compared to an uninjured control group. Patients should be informed about residual functional limitations despite improved stability.

LEVEL OF EVIDENCE

III.

Clinical and radiological results after one hundred fifteen MPFL reconstructions with or without tibial tubercle transfer in patients with recurrent patellar dislocation-a mean follow-up of 5.4 years

PURPOSE

Medial patellofemoral ligament reconstruction (MPFLR) shows low recurrent rates and high satisfaction. Reports on outcome at mid-term follow-up in a large cohort with or without tibial tubercle transfer (TTT) are scarce.

METHODS

One hundred six patients (115 knees; 24.3 ± 8.7 years) with recurrent patellar dislocation underwent MPFLR with ipsilateral gracilis autograft and were included in this retrospective follow-up study. In 43 knees, simultaneous TTT was performed for patellar maltracking due to patella alta or increased tibial tubercle trochlear groove distance (TT-TG). Kujala and subjective knee scores were recorded pre- and post-operatively.

RESULTS

Eighty-seven percent of the patients were satisfied at a mean follow-up of 5.4 ± 3.1 years. The Kujala score increased in 81.7% of all knees from 50.9 to 76.2 points (p < 0.01). Patients with a decreased Kujala score were not different in terms of follow-up time, age, trochlear dysplasia, or post-operative patellar height. The decline was related to an increase in pain, whereas functional scores remained identical. There were six patients with persisting instability, three with patellar re-dislocation. Re-operation was necessary in 24 patients (21.2%), mainly for implant removal after TTT and loss of flexion. Performing TTT had no significant influence on the subjective outcome. Patients with more than eight years of follow-up (n = 27) did not show any difference in the subjective outcome parameters, or in osteoarthritis progression.

CONCLUSION

MPFLR with and without TTT is a reliable treatment option for recurrent patellar dislocation without deterioration at mid-term follow-up. Persisting pain is a major post-operative issue that seems to be unrelated to patellofemoral anatomy.

Functional outcome after recurrent patellar dislocation : Comparison of two surgical techniques-Medial patellofemoral ligament reconstruction (MPFL) vs. Elmslie Trillat procedure

Background

There is no final consensus regarding the ideal surgical technique for the treatment of patellar dislocation. The aim of this retrospective pilot study was to describe muscle strength, body composition, self-reported physical performance, and pain in male patients after patellar dislocation treatment with two different surgical techniques: medial patellofemoral ligament (MPFL) reconstruction vs. the Elmslie-Trillat procedure.

Methods

Isokinetic testing of knee extensor muscles was performed using a Biodex System 3 pro dynamometer at an angular velocity of 60°/s. Body composition was measured with bioelectrical impedance analysis (Nutribox). Self-reported physical performance and pain were assessed by the SF-36 subscales of physical functioning, role physical and bodily pain. The outcome variables of peak torque normalized to participant’s body mass (Nm/kg), lean body mass, phase angle, self-reported physical performance, and pain were compared between the study groups.

Results

Of the 12 included male patients, 6 had been treated with MPFL reconstruction (age: median = 33 years, range = 18–38 years; BMI: median = 26 kg/m², range = 23–29) and 6 with the Elmslie-Trillat procedure (age: median = 26 years, range = 19–32 years; BMI: median = 23 kg/m², range = 19–28). No statistically significant differences were found between the groups in any outcome parameter of muscle strength, body composition, self-reported physical performance, or pain.

Conclusions

The results of the present pilot study revealed that MPFL reconstruction shows equal results to the Elmslie-Trillat procedure, with respect to isokinetic knee muscle strength, body composition, self-reported physical performance and pain in male patients suffering from recurrent patellar dislocation.

The Ribbon-shaped Femoral Footprint of the Medial Patellofemoral Ligament: Implications for Reconstruction

The medial patellofemoral ligament (MPFL) is the primary static stabilizer to lateral translation of the patella and serves as part of the medial patellar soft tissue restraints. Because of the sensitivity of MPFL graft function after reconstruction to the position of the femoral tunnel, many studies have aimed to identify the exact point of the femoral origin, as well as defining techniques to confirm this position intraoperatively. We describe the ribbon-shaped footprint of the MPFL on the medial femur and the associated difficulty in identifying the origin as a single "point." Varying isometry and biomechanical functions have been shown to exist within the most proximal and most distal fibers, suggesting the function of the MPFL may not be fully recreated with a tubular graft in a round tunnel. We review the anatomical descriptions of the elongated femoral footprint of the MPFL and describe our surgical technique to recreate this.