Tibial tuberosity transfer for episodic patellar dislocation

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.

The influence of primary treatment approach on outcomes in patients with osteochondral fracture after patellar dislocation: a case series

BACKGROUND

We characterized the relation of primary treatment approaches to the need of later surgical interventions and the outcomes of patellar dislocation in patients with patellofemoral osteochondral fracture (OCF).

METHODS

Overall, 134 patients with OCF were categorized in two groups according to treatment approach: primary surgery (operation within 90 days from injury) and conservative treatment. Data on surgical procedures, OCF characteristics, and patellofemoral anatomy were retrospectively collected. To measure subjective outcomes, 54 patients completed the knee-specific patient-reported outcome measures (PROMs) Kujala score, Tegner activity scale, the knee injury and osteoarthritis outcome score (KOOS) quality of life (QoL) subscale, and visual analog scale pain items.

RESULTS

The mean follow-up time was 4.9 years [standard deviation (SD) 2.7 years]. The primary treatment approach was surgery in 73 patients (54%) and conservative in 61 patients (46%) of whim 18 (30%) needed late surgery. Of primary surgery patients, the OCF was reimplanted in 45 patients (62%) and removed in the rest. Of all patients, 31 needed surgery in the later phase after the primary treatment approach (either reoperation or surgery after insufficient outcome of conservative treatment). In conservatively treated patients, OCF was smaller and patellofemoral joint malformation was more severe than in surgery group. Among patients who completed the PROMs, the outcomes appeared generally acceptable in both groups.

CONCLUSIONS

Although a majority of the primary treatment approaches for OCF after patellar dislocation were definitive, one-fourth of patients required surgery in the later phase. PROMs did not indicate major differences between the study groups.

Patella-Posterior Turning Point of the Distal Femur Distance Is a Potential Indicator for Diagnosing Patella Alta in Recurrent Patellar Dislocation Population

PURPOSE

To introduce a simple patellar height measurement method (patella-posterior turning point of the distal femur [P-PTP] Distance) independent of patellar anatomy with standardized patient position, and tested the reliability, validity, and diagnostic accuracy compared with commonly used ratios in knee extension.

METHODS

We retrospectively reviewed 418 computed tomography (CT) images of the knee joint in a group of patients who were diagnosed recurrent patellar dislocation (RPD). With the three-dimensional (3D) CT reconstructed knee, patellar height was qualitatively assessed by the patellar engagement with the femoral trochlea in terminal knee extension to divide RPD population into case (patella alta) and control group. With digitally reconstructed lateral radiographs, patellar height was measured with P-PTP distance (perpendicular distances between the distal edge of patella articular surface and posterior turning point of distal femur), and four commonly used ratios: Caton-Deschamps index, Modified Insall-Salvati index, Blackburne-Peel index, and Insall-Salvati index. An unpaired t-test was conducted to determine significant differences between groups. Correlation coefficient, intra- and inter-observer reliability, receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were also calculated.

RESULTS

198 knee images (198 patients) were included for final evaluation. Patella alta was present in 72 knees (36.3%) with RPD. The effect size was relatively large between the case and control group for P-PTP distance (d = -1.619; 95% CI, -1.948 to -1.286). P-PTP distance correlated moderately to strongly with four commonly used ratios (P < .001). Intraobserver and interobserver reliability was good for P-PTP distance. The AUC of the ROC curve was categorized as excellent for P-PTP distance, better than other measurements (P < .001), and the cutoff value was 4.2 mm with the highest sensitivity (86.11%) and specificity (84.92%).

CONCLUSIONS

The measurement method, P-PTP distance, showed good intra-observer and inter-observer reliability, well correlated with commonly used ratios, and presented best diagnostic accuracy among commonly used ratios for predicting RPD. P-PTP distance might be a potential indicator for identifying patella alta in RPD patients when supine and knee extended.

CLINICAL RELEVANCE

The measurement reported in this study may help in advancing clinical evaluation of patella alta, providing an alternative and simple method to measure patellar height. Standing or weight-bearing plain lateral radiographs obtained from the routine practice should be further assessed in the next step to further validate the method.

High incidence of complication following tibial tubercle surgery

OBJECTIVES

Tibial tubercle osteotomy (TTO) is a common procedure that is frequently used in the treatment of recurrent patellar instability and/or patellar chondrosis. Current estimates of TTO complications in the literature vary widely, with complication rates reaching 59 percent. This variability is due, in part, to inconsistent definitions of complication between studies. The purpose of this study was to identify our complication rate following TTO procedures, with sub-analysis of whether the complication rate was affected by: 1. An intra-articular component defined as an additional procedure that altered post-operative rehabilitation and 2. A distalization of the tubercle translation.

METHODS

All patients between May 2009 and May 2015 who underwent a TTO were retrospectively identified. Complications were defined as major (fracture of the tibia, deep infection, non-union, delayed union, arthrofibrosis, deep vein thrombosis (DVT) and loss of screw fixation) versus minor (superficial wound infection, disturbance of cutaneous sensation and delay in wound healing). Subgroup analysis of distalization versus no distalization and intra-versus extra-articular concomitant procedures were also analysed.

RESULTS

One hundred and sixty-three TTOs in 150 patients were included in the final cohort with a mean follow-up of 21.3 months. The overall complication rate was 35 major complications (21.5%) and 13 minor complications (8.0%), with a total complication rate of 29.5 percent. TTO distalization did not increase the rate of complications. DVT was only seen in the intra-articular procedure cohort (n = 3/1.8%). Arthrofibrosis was the most common complication, occurring in 17 knees.

CONCLUSION

The overall complication rate of TTOs was 29.5%, with arthrofibrosis (10.4%) as the largest complication. DVT increased with concomitant intra-articular procedure. Distalization of the tubercle compared to no distalization had no significant effect on complications.

LEVEL OF EVIDENCE

Retrospective Cohort study, level III.

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.

Radiographic and Clinical Outcomes After Tibial Tubercle Osteotomy for the Treatment of Patella Alta: A Systematic Review and Meta-analysis

BACKGROUND

Patella alta is a known risk factor for patellar instability and, in the setting of recurrent patellar instability with significant patella alta, correction of patellar height with a tibial tubercle osteotomy (TTO) may help decrease the failure of soft tissue-based stabilization.

PURPOSE

To perform a systematic review and meta-analysis of radiographic and clinical outcomes after TTO for patella alta.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

PubMed, OVID/Medline, and Cochrane databases were queried in June 2020 for studies reporting outcomes of TTO for patella alta. Data pertaining to study characteristics and design, radiographic and clinical outcome values, and incidence of complications and reoperations were extracted. DerSimonian-Laird continuous and binary random-effects models were constructed to (1) perform subgroup-based analysis of mean changes in radiographic indices after TTO and (2) quantify the pooled incidence of complications and reoperations.

RESULTS

Eight studies including 340 patients (420 knees) with a mean age of 24.7 ± 8.4 years were included. The mean follow-up was 53.1 months (range, 3-120 months), with 1 study reporting a mean follow-up of less than 2 years. The pooled mean anterior transfer was 5.6 mm; the mean medial transfer was 8.7 ± 1.3 mm; and the pooled mean distalization of the tibial tubercle was 12.2 ± 4.5 mm. Continuous random-effects meta-analysis determined that significant reductions in the mean Insall-Salvati ratio (1.40 vs 0.98, P < .001), Caton-Deschamps index (1.26 vs 0.97, P < .001), and tibial tubercle to trochlear groove ratio (18.27 vs 10.69, P < .001) were observed after TTO. The overall incidence of complications was 7.6% (95% CI, 4.8%-10.5%), while the overall incidence of reoperations was 14.3% (95% CI 6.2%-22.4%).

CONCLUSION

TTO for patellar instability in the setting of patella alta results in a significant decrease in patellar height with varying degrees of medialization depending on the utilized technique. A mean postoperative complication rate of 7.6% was reported with a reoperation incidence of 14.3%, related primarily to hardware removal.

Tibial Tuberosity-Trochlear Groove Distance and Its Components in Patients with and without Episodic Patellar Dislocation: A Study of 781 Knees

BACKGROUND

The purposes of the present study were (1) to measure the tibial tuberosity-trochlear groove distance and its components with the knee in extension, (2) to determine their diagnostic performance in distinguishing between patients with and without episodic patellar dislocation, and (3) to investigate the relationship of each component to the total tibial tuberosity-trochlear groove distance.

METHODS

We retrospectively reviewed computed tomography (CT) images of the knee joint in a group of patients with episodic patellar dislocation and a group of control subjects who were treated for another type of knee disorder in our institution between 2015 and 2021. Tibial tuberosity-trochlear groove distance, tibial tubercle lateralization, trochlear groove medialization, and knee rotation were measured on axial images. Partial correlation analysis of the measured parameters was performed after adjusting for remaining variables. Receiver operating characteristic (ROC) curves and the areas under the ROC curves (AUCs) were assessed to assess the diagnostic accuracy. A subgroup analysis based on femoral trochlear dysplasia classification was also performed.

RESULTS

After screening of 653 patients (947 knees) in our hospital's patient registry, a total of 521 patients (781 knees) were analyzed, including 541 knees (69.3%) with episodic patellar dislocation and 240 knees (30.7%) without episodic patellar dislocation (control group). The tibial tuberosity-trochlear groove distance demonstrated the best diagnostic performance, with the AUC being significantly better than that for other parameters (p < 0.001). The tibial tuberosity-trochlear groove distance was moderately to strongly correlated with knee rotation and trochlear groove medialization in the control and episodic patellar dislocation groups (p < 0.001). However, tibial tubercle lateralization showed a weak correlation with the tibial tuberosity-trochlear groove distance in the control group and moderate correlation in the episodic patellar dislocation group (p < 0.001). Knees with a type-D femoral trochlea had a significantly greater tibial tuberosity-trochlear groove distance than those with a type-A, B, or C femoral trochlea (p ≤ 0.011).

CONCLUSIONS

Tibial tuberosity-trochlear groove distance, a reliable predictor of episodic patellar dislocation, was affected more by knee rotation and trochlear groove medialization and was less affected by tibial tubercle lateralization, and it increased with an increasing grade of femoral trochlear dysplasia. The correlation of the tibial tuberosity-trochlear groove distance and its components as noted in the current study will help to achieve a better understanding of the tibial tuberosity-trochlear groove distance.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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%).

Coronal Malalignment-When and How to Perform a Tibial Tubercle Osteotomy

Coronal malalignment of the patellofemoral joint may contribute to both instability as well as pain and joint overload. The use of distal realignment procedures has evolved to include uniplanar and multiplanar osteotomies, which allows patient-specific treatment. With a careful understanding of the complex pathoanatomy, including osseous, soft tissue, and dynamic muscular factors, an appropriately designed tibial tubercle osteotomy (TTO) is an invaluable tool for the orthopedic surgeon to improve joint biomechanics and off-load articular injuries. Current techniques have improved TTO surgery to limit complications and produce reliably good results.

Surgery for patellar dislocation has evolved towards anatomical reconstructions with assessment and treatment of anatomical risk factors

PURPOSE

Increasing knowledge on the treatment of patellar dislocation has resulted in the development of new surgical techniques for patella stabilisation. National incidence and trends in surgery for patellar dislocation were examined using data from the Finnish National Hospital Discharge Register (NHDR). The hypothesis was that an increased understanding of the pathophysiology of patellar instability has increased the popularity of reconstructing damaged structures and modification of anatomical risk factors.

METHODS

Data from the years 1997-2016 were collected from the NHDR database using ICD-10 diagnostic codes and the Nomesco Classification of Surgical Procedures (NCSP) codes. Surgical procedures were categorised into subgroups representing the main surgical approaches of patellar dislocation. Total incidence of surgery for patellar dislocation and change in incidence during the study period were calculated.

RESULTS

A total of 9702 operations for patellar dislocation were performed during the study period. Median (IQR) patient age at time of primary surgery was 23 (18-34) years. The total incidence of surgeries remained stable across the study period at of 8.9 per 100,000 person-years. Incidences of ligament reconstruction, femoral osteotomies and osteochondral fragment reimplantation operations multiplied during the study period. Ligament reconstruction procedures were the most performed operations at the end of the study period.

CONCLUSION

The incidence of surgical procedures for patellar dislocation remained unchanged during the years 1997-2016. Ligament reconstruction procedures increased in popularity. Surgical techniques have shifted towards the reconstruction of damaged structures and the modification of congenital anatomical risk factors for patellar dislocation. Diversified surgical techniques have enabled the tailoring and combining of stabilizing procedures according to the patient's individual anatomy.

Medial Patellofemoral Reconstruction Using Quadriceps Tendon Autograft, Tibial Tubercle Osteotomy, and Sulcus-Deepening Trochleoplasty for Patellar Instability

Recurrent patellar dislocations have been correlated with an elevated risk of further patellar dislocations, often requiring surgical treatment. Risk factors include medial patellofemoral ligament (MPFL) tears, patella alta, trochlear dysplasia, and an increased tibial tubercle-trochlear groove distance. Surgical management must be based on a patient's unique joint pathoanatomy and may require MPFL reconstruction with tibial tubercle osteotomy or trochleoplasty either alone or in combination. This article discusses our preferred technique for surgical treatment of recurrent patellar instability with MPFL reconstruction using a quadriceps tendon autograft, an open trochleoplasty, and a tibial tubercle osteotomy for patients with patella alta, trochlear dysplasia, and an increased tibial tubercle-trochlear groove distance.

Return-to-Play Guidelines After Patellar Instability Surgery Requiring Bony Realignment: A Systematic Review

Background

Recurrent patellar instability can be treated nonoperatively or surgically, and surgical management may vary based on the causative pathology in the structures surrounding the patella. Although isolated soft tissue reconstruction is among the most common operative treatments, certain patient populations require bony realignment for adequate stabilization.

Purpose

To evaluate postoperative guidelines, including return to play and rehabilitation, after bony procedures involving the tibial tubercle for patellar instability.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic review on return-to-play guidelines was conducted with studies published from 1997 to 2019 that detailed procedures involving bony realignment by tibial tubercle osteotomies and tibial tubercle transfers with or without soft tissue reconstruction. Exclusion criteria included animal or cadaveric studies, basic science articles, nonsurgical rehabilitation protocols, and patients with mean age <18 years. Studies were assessed for return-to-play criteria, rehabilitation protocols, and bias.

Results

Included in the review were 39 studies with a total of 1477 patients and 1598 knees. Mean patient age ranged from 17.5 to 34.0 years, and mean follow-up ranged from 23 to 161 months. All 39 studies described postoperative rehabilitation; however, only 16 studies specifically outlined return-to-play criteria. The most commonly cited return-to-play criterion was quadriceps strength (62.5%). Range of motion (50.0%), physical therapy protocols (18.8%), and radiographic evidence of healing (18.8%) were other cited objective criteria for return-to-play. Four of 16 (25.0%) studies described subjective criteria for return to play, including pain, swelling, and patient comfort and confidence. Of the 11 studies that described a timeline for return to play, the range was between 2 and 6 months.

Conclusion

The results revealed that 100% of papers evaluated lacked adequate return-to-play guidelines. Moreover, timelines significantly varied among studies. More clearly defined return-to-play guidelines after tibial tubercle transfer for patellar instability are required.

Clinical outcomes of medial retinaculum plasty versus MPFL reconstruction with concomitant tibial tubercle transfer: a retrospective study

PURPOSE

To elucidate the clinical outcomes of medial retinaculum plasty versus MPFL reconstruction with concomitant tibial tubercle transfer.

METHODS

From January 2014 to July 2018, 57 patients who underwent tibial tubercle transfer combined with medial retinaculum plasty or MPFL reconstruction were enrolled in the present study. The 57 patients were divided into two comparison groups according to the therapeutic protocol. The 25 patients in group I underwent the medial retinaculum plasty and tibial tubercle transfer. The 32 patients in group II underwent the MPFL reconstruction and tibial tubercle transfer. Clinical outcomes were assessed using the knee injury and osteoarthritis outcome score, Kujala score, congruence angle, patellar tilt angle, patellar lateral shift, tibial tuberosity-trochlear groove distance and Caton-Deschamps Index. The clinical outcomes were compared between the two groups preoperatively and at the time of the last follow-up.

RESULTS

Significant improvement was seen in both groups postoperatively (P < 0.05). There were no significant differences in the knee injury and osteoarthritis outcome score, Kujala score, congruence angle, patellar tilt angle, patellar lateral shift, tibial tuberosity-trochlear groove distance and Caton-Deschamps Index between the two groups (P > 0.05).

CONCLUSION

The combined medial retinaculum plasty and tibial tubercle transfer achieved similar clinical outcomes versus the MPFL reconstruction with concomitant TTT. This therapeutic protocol was a good option in treatment of patellar dislocation with increased TT-TG distance or patella alta.

How Does Isolated Medial Patellofemoral Ligament Reconstruction Influence Patellar Height?

BACKGROUND

Reconstruction of the medial patellofemoral ligament (MPFL) is the gold standard treatment for recurrent patellar dislocation. Patella alta has been reported in about half of patients with recurrent patellofemoral instability.

HYPOTHESIS

MPFL reconstruction (MPFLr) has a beneficial role in the correction of patellar height in patients with mild patella alta (Caton-Deschamps index [CDI] between 1.20 and 1.40).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Skeletally mature patients, with no history of previous or concomitant knee surgical procedures, who underwent isolated MPFLr using hamstring autograft for recurrent patellar instability between 2005 and 2018, were included in this study. The authors calculated CDI, modified Insall-Salvati index (MISI), and Blackburne-Peel index (BPI) ratios. Measurements done by 2 independent observers were calculated and used to compare pre- and postoperative patellar height (patella alta: CDI >1.20).

RESULTS

A total of 89 patients (95 knees) were included in the study, with a mean age of 25.0 years (range, 15.0-45.0 years). There were 70% women and 30% men. We found patella alta in 35.8% of cases preoperatively. Among them, 79.4% had reduced patellar height indices, within normal limits, postoperatively (mean follow-up, 18.4 ± 12.0 months). All the ratios showed a significant reduction in patellar height after surgery (CDI: 0.19 [range, -0.05, 0.60]; MISI: 0.22 [-0.14, 0.76]; BPI: 0.18 [-0.08, 0.59]; P < .00001). The CDI of 79.4% of the study knees was reduced to within normal limits postoperatively. The CDI was maintained within normal limits postoperatively in 93.4% of the knees with normal patellar height and reduced to normal in 50% of the knees with severe patella alta before surgery . No patient reported patella infera before surgery, whereas this condition was found in 8.2% of study patients postoperatively. A moderate correlation was reported between preoperative radiographic indices and their reduction after surgery (CDI: P < .001, ρ = 0.39; MISI: P < .001, ρ = 0.39; BPI: P < .001, ρ = 0.48).

CONCLUSION

The higher the preoperative patellar height, the more important is the lowering effect of MPFLr using the hamstring for patellar instability. Bony procedures should not be indicated in patients with patellar instability and a CDI between 1.20 and 1.40.

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

BACKGROUND

Multiple studies have demonstrated that a number of demographic and pathoanatomic characteristics are associated with patellofemoral instability, recurrence of instability, and less satisfactory results following medial patellofemoral ligament reconstruction (MPFL-R). Despite the growing volume of research, the relationship of risk factors to patient-reported outcome after MPFL-R is unclear.

PURPOSE

To determine if certain pathoanatomic and demographic factors predict disease-specific quality-of-life outcome after isolated MPFL-R for symptomatic patellofemoral instability.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study analyzed 224 isolated MPFL-Rs. Demographic data were collected, including age at first dislocation, sex, and presence of bilateral instability. Pathoanatomic risk factors included the presence of high-grade trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, patella alta ratio, Beighton score, and patellar tilt. Other factors included femoral tunnel position accuracy and WARPS/STAID score. Descriptive analyses were conducted, followed by calculation of individual Spearman rank correlation coefficients for the predictor variables versus the Banff Patellofemoral Instability Instrument (BPII) scores. A multivariable regression with stepwise selection was employed to establish the final model predicting BPII score, with all significant variables for alpha ≤ .05 included in the final model.

RESULTS

The cohort of 224 patients included 66 (29.5%) males and 158 (70.5%) females, with a mean age of 24.1 years and a mean body mass index of 23.9 kg/m². The mean age of first patellar dislocation was 15.7 years, and 41.4% of patients had bilateral instability. Pathoanatomic variables within the cohort included the following: high-grade trochlear dysplasia = 41%; mean TT-TG = 14.6 mm, with 16.8% of patients demonstrating a TT-TG ≥18 mm; mean Caton-Deschamps ratio = 1.09, with 22% of patients demonstrating a ratio ≥1.2; and positive Beighton score = 37.5%. The mean BPII score at postoperative 2 years was 67.1 out of 100. A stepwise elimination in the regression model demonstrated no statistically significant 3- or 2-way relationships. Assessment of individual variables indicated that bilateral symptoms (P = .004), higher age at first dislocation (P = .024), and femoral tunnel position >10 mm from the Schöttle point (P = .042) were statistically significant predictors of lower quality-of-life scores. The R² value for the regression analysis model was 0.07.

CONCLUSION

In this large cohort of patients undergoing isolated MPFL-R for symptomatic lateral patellofemoral instability, a multivariable forward stepwise regression demonstrated that bilateral symptoms, femoral tunnel position, and age at first dislocation were statistically significant predictors of lower postoperative BPII scores. No anatomic risk factors were predictive of quality-of-life outcome score 2 years after MPFL-R surgery. The R² value indicated that there were many other important contributing factors affecting BPII outcome scores than those explored in this study.

Reconstruction of the medial patellofemoral ligament and reinforcement of the medial patellotibial ligament is an effective treatment for patellofemoral instability with patella alta

PURPOSE

To evaluate the clinical outcome of the combined reconstruction of the medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) for patellar instability with patella alta.

METHODS

A total of 108 patients underwent a combined reconstruction of the MPFL and MPTL, and 58 patients were included in this study. The clinical results were evaluated and compared using the International Knee Documentation Committee (IKDC) scores, Kujala scores, and visual analogue scale (VAS) scores. The tibial tuberosity-trochlear groove (TT-TG) distance, three indices of patellar height (Insall-Salvati ratio, modified Insall-Salvati ratio, and Caton-Deschamps index), and patellar shift and tilt were defined preoperatively and at the 12- and 24-month follow-up visits.

RESULTS

At the 12- and 24-month follow-up visits, 86.2% (50/58) and 87.9% (51/58) of the subjective outcomes were excellent, 5/58 (8.6%) and 4/58 (6.9%) were good, 1/58 (1.7%) and 2/58 (3.4%) were fair, and 2/58 (3.4%) and 1/58 (1.7%) were poor. There were significant improvements in the IKDC scores, from 51.9 ± 13.8 preoperatively to 80 ± 19.2 (P < 0.05) at 12 months and 85 ± 13.9 (P < 0.05) at 24 months; Kujala scores, from 55.1 ± 15.2 preoperatively to 82.6 ± 14.9 (P < 0.05) at 12 months and 89.5 ± 10.2 (P < 0.05) at 24 months; and VAS scores, from 58 ± 11 preoperatively to 12 ± 5 (P < 0.05) at 12 months and 11 ± 4 (P < 0.05) at 24 months. The patellar tilt, patellar shift, Insall-Salvati ratio, modified Insall-Salvati ratio, Caton-Deschamps index, and TT-TG distance all decreased significantly compared with the preoperative values, and there were no significant differences between the values at the 12- and 24-month follow-ups.

CONCLUSION

The results of this study show that a combined reconstruction of the MPFL and MPTL is an effective treatment for patellar instability with patella alta. This article emphasizes the combined effect of MPFL and MPTL instead of MPFL alone and provides an effective option for the treatment of recurrent patellar dislocation with patella alta.

LEVEL OF EVIDENCE

Case series, Level IV.

Lateral retinacular release is not recommended in association to MPFL reconstruction in recurrent patellar dislocation

PURPOSE

Reconstruction of the medial patellofemoral ligament (MPFL) has become the gold standard for the treatment of the recurrent patellar dislocation (RPD). Lateral retinacular release can be performed in association with MPFL reconstruction, but the effect on outcomes is not clear. To evaluate the effect of lateral release on outcomes following MPFL reconstruction is the aim of this study. It is hypothesized that isolated MPFL reconstruction was not inferior to MPFL reconstruction and lateral retinacular release in terms of IKDC subjective score and patellar tilt (PT).

METHODS

Patients between ages 18 and 45 scheduled to undergo MPFL reconstruction without an associated bony procedure (tibial tubercle osteotomy or trochleoplasty) were randomized to isolated MPFL reconstruction or MPFL reconstruction (no LRR group) and arthroscopic LRR (LRR group). Evaluation criteria were subjective IKDC score as the primary outcome and PT evaluated with a CT-scan. PT was evaluated with the quadriceps relaxed (PTQR) and contracted (PTQC).

RESULTS

Of 43 patients included in the trial, 7 were lost of follow-up, 3 were not able to complete evaluation because of medical reasons, and 33 patients were evaluated with a minimum of 12 months and a median follow-up of 24 (12-60) months. The average subjective IKDC score was at 86 ± 20 (29-94) in the LRR group and 82 ± 15 (39-95) in the no LRR group (p = 0.45). The PTQR was at 22° ± 7° (13-37) in the LRR group and 21 ± 10 (4-37) in the no LRR group (n.s.). The PTQC was at 27° ± 9° (12-40) in the LRR group and 25 ± 12 (5-45) in the no LRR group (n.s.). No complications were noted in either group.

CONCLUSIONS

No significant differences were found in subjective IKDC score or patellar tilt based on the addition of an arthroscopic LRR to an MPFL reconstruction in patients with RPD not undergoing associated bony procedures. There is no indication to a systematic lateral retinacular release in association with MPFL reconstruction in the treatment of RPD.

LEVEL OF EVIDENCE

II.

Medial patellofemoral ligament reconstruction with or without tibial tubercle transfer is an effective treatment for patellofemoral instability

PURPOSE

The hypotheses were that medial patellofemoral ligament reconstruction (MPFLr) would improve the long-term symptoms of patellofemoral Instability (PFI) and control patellar tilt, based on computed tomography (CT), and that the addition of a TT transfer, when it is necessary, would not deteriorate the outcome. The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of a large series of MPFLr, either isolated or associated with a TT transfer.

METHODS

From 133 MPFLr with a minimum of 4 years postoperatively, three groups were defined: isolated MPFLr, MPFLr with tibial tubercle (TT) medialisation or MPFLr with TT medialisation and distalisation. IKDC and Kujala scores were evaluated. Patellar tilt was evaluated on the patient's preoperative and the last available radiograph, and on CT scan measurements performed preoperatively and at 6-month postoperatively.

RESULTS

The mean follow-up was 6.3 ± 1.7 years [4.1-10.3] and four patients reported recurrent patellar dislocation. Between pre and postoperative at last follow-up a significant improvement in IKDC and Kujala functional scores was observed (P < 0.01), with no difference between the three groups. Regarding patellar tilt, there were significant decreases in Laurin and Merchant angles and an improvement of the Maldague stage (P < 0.01). The CT analysis of patellar tilt also demonstrates a significant improvement of the patella tilt (P < 0.01). The control of the patella tilt was correlated with a good functional result (P < 0.01).

CONCLUSION

The MPFLr, whether isolated or associated with a TT transfer, provides good long-term clinical and radiological outcomes with a low rate of recurrence. The addition of a TT transfer, when necessary, results in the same good outcomes. This article provides a guide for surgeons evaluating PFI to choose the most appropriate procedure.

LEVEL OF EVIDENCE

IV.

Does patella alta lead to worse clinical outcome in patients who undergo isolated medial patellofemoral ligament reconstruction? A systematic review

INTRODUCTION

The aim of this systematic review is to determine the effect of patella height on clinical outcomes after isolated MPFL reconstruction for patella instability. Our primary hypothesis is that patients with patella alta report similar outcomes after isolated MPFL reconstruction compared to patients with normal patella height.

METHODS

A review of the literature was performed according to the PRISMA guidelines. PubMed, EMBASE, and the Cochrane Library were searched from inception to January 10th 2018. Studies were identified using synonyms for "medial patellofemoral ligament", "reconstruction" and "patella alta".

RESULTS

The search resulted in 467 reports on PubMed, 175 on EMBASE and 3 on the Cochrane Library. We included and analyzed in detail six studies describing outcomes after isolated medial patellofemoral ligament reconstruction with regard to patellar height. We found that both patients with patella alta and normal patella height reported satisfactory outcomes after isolated medial patellofemoral ligament reconstruction. However, because of applied exclusion criteria in the included studies the total number of patients with severe patella alta was small (13/74 patients with patella alta, 18%).

CONCLUSIONS

Based on the current literature we suggest that additional tibial tubercle distalisation is not mandatory in patients with mild patella alta (Caton-Deschamps Index 1.2-1.4). To assess the best indications for different surgical procedures for patients with patella instability future research is needed to develop a clear and uniform definition of relevant patella alta.

LEVEL OF EVIDENCE

III.

When and How Far to Move the Tibial Tuberosity in Patients With Patellar Instability

The many factors contributing to patellar instability have led to various surgical techniques that are used commonly today. When surgery is deemed necessary, the operation should be tailored to the patient's specific pathoanatomy. Patients with malalignment can often be stabilized by moving the tibial tuberosity to a more medial, anteromedial, or distal position. Subsequent changes in the forces acting on the patellofemoral joint will depend on the direction and distance of the tuberosity repositioning. When planning tuberosity osteotomies, it is crucial to understand how to use clinical and imaging modalities to measure and quantify tuberosity position accurately to achieve the desired degree of realignment.

Surgical Treatment of Objective Patellar Instability: Long-Term Results

Purpose  To evaluate the long-term results of classical "à la carte" surgical treatment of objective patellar instability as proposed by Dejour in 1987. Methods  A multicentric retrospective study was conducted evaluating patients that underwent surgical procedure with a 10-year minimum follow-up (mean 12.7; range, 10-15). Surgical procedures were medial transfer of the tibial tubercle transfer according to Elmslie and Trillat et al in 38 cases, plasty of the vastus medialis obliquus according to Insall in 15 cases, open lateral retinacular release in 13 cases, capsuloplasty in 3 cases, and trochleoplasty in 1 case. Different combinations of surgical procedures were adopted according to the pathological features. Subjective outcome was assessed with the visual analog scale (VAS), Kujala score, subjective International Knee Documentation Committee (IKDC) score, Tegner score, and Crosby and Insall scale. Radiographic exams were used to assess the patellar tilt by the Laurin's angle and patellofemoral osteoarthritis (OA) according to the Iwano radiological OA scale. Results  Forty patients were evaluated. Subjectively, 60% of patients achieved a result judged good, 34% sufficient, and 6% poor. There were only two cases of recurrence of instability. Mean score results were Kujala score 73.4 ± 9.9 (range, 55-95), VAS 4.5 ± 1.2 (range, 1-6), IKDC 64.8 ± 7.9 (range, 51-88), and Tegner score 4. Only nine patients returned to sports activities). Ten patients developed a grade I patellofemoral OA, 8 patients a grade II, and 22 patients a grade III. Average patellar tilt was 10° ±  3.9°. Conclusion  This retrospective study showed that the traditional surgical procedure was successful for the treatment of patellar instability, but it did not prevent symptomatic patellofemoral OA. Level of Evidence  Level IV, retrospective case series.

Clinical outcome in MPFL reconstruction with and without tuberositas transposition

PURPOSE

There are several surgical options for recurrent patella dislocations. As the reconstruction of the medial patellofemoral ligament (MPFL) has been proven to restore stability, it has become more accepted. Aim of this study was to investigate the clinical outcome after MPFL reconstruction as an isolated procedure or in association with a transposition of the tibial tubercle (in case of patella alta or an excessive TT-TG) in a large prospective cohort study. Additionally, the effect on patellar height was analysed radiographically using the Caton-Deschamps index.

METHODS

In a large prospective cohort study of 129 knees in 124 patients (81 females, 48 males, mean age 22.8 ± 7.7 years), 91 knees received primary MPFL reconstruction (group 1) and 38 were a combination with a transposition of the tibial tubercle (group 2). The clinical follow-up was evaluated using KOOS and Kujala scores preoperatively and 1 year postoperatively. Patient satisfaction, complications and revision surgery were recorded.

RESULTS

Overall, Kujala improved significantly from 53.5 (SD 22.7) preoperatively to 74.7 (SD 20.5) postoperatively (p < 0.01). All KOOS subdomains improved significantly (p < 0.01). No significant difference for Kujala score between groups was noticed. Revision rate was (5/129) 3.9 %. Reconstruction was supplemented with a transfer of the tibial tuberosity in (38/129) 29.4 % of the cases and shows a comparable outcome.

CONCLUSION

MPFL reconstruction is a viable treatment option for episodic patellar dislocation. A concomitant tuberositas transposition is useful in selected patients.

LEVEL OF EVIDENCE

I.

Risk of vascular injury when screw drilling for tibial tuberosity transfer

PURPOSE

During tibial tubercle transfer, popliteal vessels are at risk from drills and screws. The risk is around 0.11%, as described in the literature. We reviewed knee injected CT scan for analysis of the location of arteries, identified landmarks allowing minimizing risks, and defined a safe zone.

MATERIAL AND METHOD

Distances between the posterior cortex and arteries were measured on CT scans from 30 adults (60 knees) at three levels (proximal part of the tibial tuberosity, 20 mm and 40 mm distally). Data were used to create a "risk map" with different angular sectors where the frequency of the presence of arteries was analyzed in each area. We also analyzed the position of 68 screws of 47 patients who underwent a medial tibial tuberosity transfer.

RESULTS

The nearest distance between artery and the posterior tibial cortex was found at the level corresponding to the top of the tuberosity with less than 1 mm, while the largest distance was found at the distal level. We were able to define a safe zone for drilling through the posterior tibial cortex which allows a safe fixation for the screws. This zone corresponds to the medial third of the posterior cortex. When the safe zone is not respected, screws that overtake the posterior cortex may be close to arteries as observed for 37 of the 68 screws analyzed.

CONCLUSION

We described new landmarks and recommendations to avoid this complication during tibial tuberosity transfer.

Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies

Patellar instability is a common clinical problem encountered by orthopedic surgeons specializing in the knee. For patients with chronic lateral patellar instability, the standard surgical approach is to stabilize the patella through a medial patellofemoral ligament (MPFL) reconstruction. Foreseeably, an increasing number of revision surgeries of the reconstructed MPFL will be seen in upcoming years. In this paper, the causes of failed MPFL reconstruction are analyzed: (1) incorrect surgical indication or inappropriate surgical technique/patient selection; (2) a technical error; and (3) an incorrect assessment of the concomitant risk factors for instability. An understanding of the anatomy and biomechanics of the MPFL and cautiousness with the imaging techniques while favoring clinical over radiological findings and the use of common sense to determine the adequate surgical technique for each particular case, are critical to minimizing MPFL surgery failure. Additionally, our approach to dealing with failure after primary MPFL reconstruction is also presented.

An Algorithmic Approach to the Management of Recurrent Lateral Patellar Dislocation

High-level evidence supports nonoperative treatment for first-time lateral acute patellar dislocations. Surgical intervention is often indicated for recurrent dislocations. Recurrent instability is often multifactorial and can be the result of a combination of coronal limb malalignment, patella alta, malrotation secondary to internal femoral or external tibial torsion, a dysplastic trochlea, or disrupted and weakened medial soft tissue, including the medial patellofemoral ligament (MPFL) and the vastus medialis obliquus. MPFL reconstruction requires precise graft placement for restoration of anatomy and minimal graft tension. MPFL reconstruction is safe to perform in skeletally immature patients and in revision surgical settings. Distal realignment procedures should be implemented in recurrent instability associated with patella alta, increased tibial tubercle-trochlear groove distances, and lateral and distal patellar chondrosis. Groove-deepening trochleoplasty for Dejour type-B and type-D dysplasia or a lateral elevation or proximal recession trochleoplasty for Dejour type-C dysplasia may be a component of the treatment algorithm; however, clinical outcome data are lacking. In addition, trochleoplasty is technically challenging and has a risk of substantial complications.

Patellofemoral Joint Reconstruction for Patellar Instability: Medial Patellofemoral Ligament Reconstruction, Trochleoplasty, and Tibial Tubercle Osteotomy

Recurrent patellar instability can be very debilitating and may require surgical intervention. A thorough workup must be completed in this subset of patients. Risk factors for recurrent instability include patella alta, trochlear dysplasia, an increased tibial tubercle-trochlear groove distance, and insufficiencies in the medial retinacular structures. Necessary treatment of these risk factors, once identified, should be addressed surgically. Patellofemoral reconstruction must be individually tailored to each patient's anatomy and may necessitate medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, or trochleoplasty in any combination or as a standalone procedure. This article details our technique for surgical treatment of recurrent patellar instability with a medial patellofemoral ligament reconstruction, an open trochleoplasty, and a tibial tubercle osteotomy for patients with severe trochlear dysplasia, an increased tibial tubercle-trochlear groove distance, or patella alta.

Results of anatomic gracilis MPFL reconstruction with precise tensioning

BACKGROUND

The medial patellofemoral ligament (MPFL) is the most commonly injured structure in patients with objective patellar instability. The objective of this study was to prospectively evaluate the clinical and radiographic results of MPFL reconstruction in 50 patients with chronic patellar instability.

METHODS

Fifty patients with chronic patellar instability, aged 15-39 years, were included. The MPFL was reconstructed using a free gracilis autograft tendon. Two anchors were used for patellar fixation, and femoral fixation was achieved with an interference screw placed into a tunnel between the adductor tubercle and medial epicondyle. The graft was tensioned to 10 N with the knee in 30° flexion. IKDC and Kujala scores were assessed pre- and post-operatively. Patellar tilt was measured from CT scans with the quadriceps relaxed and contracted, both pre- and post-operatively.

RESULTS

The follow-up period was 7 to 44 months (mean: 25 months, SD 10.3). The mean raw IKDC score increased from 51.5 preoperatively to 71.7 at last follow-up, the mean overall IKDC score increased from 38.5 to 61.7 and the Kujala score increased from 48.3 to 82.4. On CT scans, the mean patellar tilt went from 24° to 16.2° with the quadriceps relaxed and 27.7° to 18.1° in contraction. No recurrent dislocation was observed.

CONCLUSION

This technique of MPFL reconstruction provided significant improvements in IKDC and Kujala scores and significant reduction in patellar tilt. No recurrent dislocations were observed during the study period.

Semitendinosus Tendon Transfer Associated With Distal Alignment for Patella Alta in a Patient With Recurrent Dislocations

Patellofemoral instability is characterized by pain during normal daily activities and frequent dislocation events. In the reported case, an adolescent girl, aged 15 years, affected by left patellofemoral instability, underwent surgery with a double technique comprising tibial tubercle distalization and medial patellofemoral ligament reconstruction. In case of patella alta associated with patellofemoral instability, surgical treatment should focus on medial patellofemoral ligament repair and on recurrent instability prevention.

How to Deal With Chronic Patellar Instability: What Does the Literature Tell Us?

CONTEXT

Patellar instability is a common clinical problem, affecting between 7 and 49 people per 100,000. However, not all patellar instabilities are equal, the etiology of the disorder is multifactorial, and a clear understanding of the cause of instability is crucial for appropriate surgical treatment. The goal of this article is to identify how to best treat patellar instability to provide good outcomes and hopefully prevent future osteoarthritis.

EVIDENCE ACQUISITION

A PubMed search from 1983 through May 2015.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Several subpopulations of patients with chronic patellar instability exist: (1) lateral patellar instability during the early arc of knee flexion (0°-30°), (2) lateral patellar instability persisting beyond 30° of knee flexion, (3) lateral patellar instability in greater knee flexion, and (4) medial patellar instability. In patients with lateral instability during the early arc of knee flexion, the medial patellofemoral deficiency is the essential lesion. Persistent instability beyond 30° of knee flexion suggests an unusually high patella, severe trochlear dysplasia, pathologic increment of the tibial tuberosity-trochlear groove distance, or a combination of these factors. In patients with lateral instability in greater knee flexion, increasing and unbalanced tension in the extensors pulls the patella out of the groove as the knee is flexed. Finally, medial patellar instability is an objective iatrogenic condition that appears after realignment surgery in the vast majority of cases.

CONCLUSION

The etiology of chronic patellar instability is multifactorial, and its treatment must therefore be personalized.

STRENGTH OF RECOMMENDATION TAXONOMY SORT

B.

Modified Technique of Tibial Tuberosity Transfer

Tibial tuberosity transfer is a well-established procedure in the treatment of patellar instability and in selected cases of anterior knee pain. Several techniques have been advocated in the literature. Some of the common complications associated with this procedure have been pain and discomfort due to prominent screw heads, necessitating their removal; nonunion and delayed union of the osteotomy; and failure of fixation. Tibial fractures have also been reported in some case reports. We present our technique of tibial tuberosity transfer using two 4-mm cannulated screws for stabilization of the tuberosity fragment. We have used this technique either for isolated tibial tuberosity transfer or as part of a combined procedure along with medial patellofemoral ligament reconstruction in treating patellar instability. Using this technique, we have encountered no patients with wound problems, nonunion, delayed union, or loss of fixation and only 1 patient with a metal work problem needing a second procedure for its removal. We attribute our good outcomes to the preservation of the soft-tissue attachments to the tuberosity fragment; minimal soft-tissue dissection, which allows rapid bony consolidation of the osteotomy, which in turn allows accelerated rehabilitation; and the use of 4-mm cannulated screws for fixation of the osteotomy, minimizing the potential for metal work problems.

Medial patellofemoral ligament reconstruction: clinical and radiographic results in a series of 90 cases

INTRODUCTION

Among the numerous techniques available, medial patellofemoral ligament (MPFL) reconstruction is increasingly used for the surgical treatment of objective patellar instability. The main objective of the present study was to assess efficacy in preventing recurrence of patellar dislocation and in correcting radiographic patellar tilt. The study hypothesis was that MPFL reconstruction, isolated or with associated bone surgery, by restoring "favorable" graft anisometry, provides a good trade-off between patellar stability and absence of postoperative stiffness.

MATERIALS AND METHODS

Eighty-seven patients (90 reconstructions) presenting with objective patellar instability were prospectively included. The standardized procedure comprised MPFL reconstruction using the gracilis tendon. Femoral fixation used an interference screw in a blind tunnel between the adductor magnus tubercle and the medial epicondyle; patellar fixation used 2 anchors. Complementary distal bone graft was associated in 21 patients due to a preoperative tibial tubercle-trochlear groove (TT-TG) distance exceeding 20mm or to patella alta. Functional IKDC and Kujala scores and radiographic measurement of patellar tilt and femoral tunnel position were assessed preoperatively and at end of follow-up.

RESULTS

Mean follow-up was 24.3months (range, 6-49months). Three patients showed recurrence of patellar dislocation. Mean Kujala score rose from 53.88 preoperatively to 86.24 postoperatively, and mean real IKDC score from 45.15 to 73.92 (P<0.001). Patellar tilt decreased significantly between pre- and postoperative X-ray (P<0.001).

DISCUSSION

MPFL gracilis reconstruction provides good clinical results and good radiologic correction of patellar tilt, making it a technique of choice in the treatment of objective patellar instability.

LEVEL OF EVIDENCE

Level IV. Retrospective case series study.

Long-term follow-up of nonoperatively and operatively treated acute primary patellar dislocation in skeletally immature patients

Purpose. The present study reports a long-term follow-up of acute primary patellar dislocation in patients with open physes. The purpose of the study was to evaluate knee function and recurrence rates after surgical and nonsurgical treatment of patellar dislocation. Methods. A total of 51 patients, including 29 girls and 22 boys, who were 9–14 years of age at the time of injury, were retrospectively evaluated. The minimum follow-up time was 5 years. Thigh muscle torque, range of motion, the squat test, the knee injury and osteoarthritis outcome score (KOOS), the Kujala score, and the recurrence rate were registered. Radiological predisposing factors at the time of injury were determined. Results. Quality of life and sports/recreation were the most affected subscales, according to KOOS, and a reduced Kujala score was also observed in all treatment groups. The surgically treated patients had a significantly lower recurrence rate. Those patients also exhibited reduced muscle performance, with a hamstring to quadriceps ratio (H/Q) of 1.03. The recurrence rate was not correlated with knee function. Conclusions. Patellar dislocation in children influences subjective knee function in the long term. Surgery appears to reduce the recurrence rate, but subjective knee function was not restored.

Introduction of a classification system for patients with patellofemoral instability (WARPS and STAID)

PURPOSE

The primary purpose of this paper is to introduce the WARPS/STAID classification system for patellofemoral instability. The secondary purpose is to establish the validity and reliability of the WARPS/STAID classification system.

METHODS

Patients (n = 31) with a confirmed diagnosis of patellofemoral instability underwent a thorough knee history and physical examination with 3 raters. The raters graded each component of the WARPS/STAID classification system on a visual analogue scale (VAS). A single Global VAS WARPS/STAID score was graded after all other components of the classification system were completed. Intraclass correlation coefficient (ICC 2, 3) was calculated for each metric of the classification scale and for the Global score. Concurrent validity was assessed by correlating the WARPS/STAID score with the Kujala score. Subjects were assigned to one of three categories (WARPS, STAID, or mixed characteristics) according to the Total WARPS/STAID score to determine the level of agreement between the three raters.

RESULTS

Intraclass correlation coefficient (ICC 2, 3) of the WARPS/STAID classification continuum ranged between 0.73 and 0.91 for the individual metrics of the classification. The ICC (2, 3) for the Global WARPS/STAID score was 0.75. The mean Kujala score (m = 61, SD 18) was significantly correlated with the total WARPS/STAID score (r = 0.387, p < 0.05). The majority of subjects were assigned to either the WARPS or STAID categories.

CONCLUSION

This study introduced the WARPS/STAID classification system and established both validity and reliability in subjects with patellofemoral instability.

LEVEL OF EVIDENCE

II.

The position of the tibia tubercle in 0°-90° flexion: comparing patients with patella dislocation to healthy volunteers

PURPOSE

The aim of this study was to measure the tibia tubercle trochlea groove distance (TT-TG) as a function of knee flexion. Our hypothesis was that there is a different pattern in healthy volunteers and patients with patella instability (PFI).

METHODS

Thirty-six knees of 30 patients with at least one dislocation of the patella and 30 knees of 30 healthy volunteers as control group were analysed with magnetic resonance imaging by three different observers. The TT-TG was measured in steps of 15° between 0° and 90° of knee flexion. Furthermore, the alignment of the leg (MA), the femur torsion (FTor) and the tibia torsion (TTor) was calculated.

RESULTS

The TT-TG was higher in patients compared to volunteers and in extension compared to flexion. This difference was statistically significant (p<0.05). Most of the patients with a TT-TG above 20 mm in extension showed a high decrease in flexion to normal values. In some patients, this compensating mechanism fails. MA, FTor and TTor were not different in patients and control group (n.s.).

CONCLUSION

The TT-TG distance is dynamic and decreased significantly during flexion in knees with PFI and healthy volunteers. However, there were a small number of patients in the PFI group where this compensation mechanism did not work. Therefore, the decision to perform a tibia tubercle osteotomy should not be based on one single measurement in extension or 30° of knee flexion.

LEVEL OF EVIDENCE

II.

Distal realignment: indications, technique, and results

When appropriately indicated, distal realignment procedures can produce consistent clinical results. Indications for distal realignment include lateral patellofemoral instability, anterior knee pain with associated lateral or distal patellofemoral cartilage lesion, and cases with significant lateral patellofemoral overload or tilt. In cases of patellofemoral instability, it is important to determine whether proximal stabilization, distal realignment, or both is needed. If distal realignment is indicated, several anatomic variables must be considered to determine the location and obliquity of the osteotomy when using multiplanar osteotomy techniques.

Triple positioning of tibial tubercle osteotomy for patellofemoral disorders

BACKGROUND AND PURPOSE

Patellofemoral disorders are often associated with patellofemoral malalignment. Tibial tubercle transfer is an effective method to correct the patellofemoral malalignment. This study evaluated the long-term results of triple positioning of tibial tubercle osteotomy for refractory patellofemoral disorders with 10-year follow-up.

PATIENTS AND METHODS

Fifty-six patients with 62 knees underwent triple positioning of tibial tubercle osteotomy for refractory patellofemoral disorders. All patients received standard rehabilitation protocol postoperatively. The average length of follow-up was 128.5±9.8 months (range 116 to 149). The evaluations included pain score, Kujala patellofemoral score, Lysholm score and radiograph of the knee.

RESULTS

The overall clinical results were excellent in 41.9%, good in 37%, fair in 12.9% and poor in 5% at 1 year; and 29% excellent, 41% good, 18.3% fair and 9.3% poor at 10 years. Satisfactory results were 78.9% and 70.9%, and unsatisfactory results 21.1% and 29.1% at 1 year and 10 years respectively. There was no correlation of clinical outcomes with age, sex, body weight and height and preoperative pain score. However, there was a positive correlation of clinical outcomes with the improvement of the congruence angle on postoperative X-rays of the knee, and a negative correlation of clinical outcome with the severity of articular cartilage damage assessed in arthroscopy. The complications included 1 non-union and 1 infection with non-union.

CONCLUSION

Triple positioning of tibial tubercle osteotomy is effective and long lasting in patients with patellofemoral disorders with 70.9% satisfactory results at 10-year follow-up.

LEVEL OF EVIDENCE

IV (refer to instructions for detailed description on the level of evidence).

Patellar instability with and without trochlear dysplasia: new arthroscopic medial soft tissue plication with pullout technique

The aim of this study was to analyze clinical and radiologic results of an arthroscopic medial plication with the pullout technique and to define indications and limitations of this procedure for patellar instability. Records of 45 patients treated for patellar instability with arthroscopic medial plication with the pullout technique were reviewed. The mean patient age was 22.8±8.3 years. The tibial tuberosity-trochlear groove distance, trochlear depth (TD), and Insall-Salvati ratio were measured using magnetic resonance imaging taken preoperatively. Patients were evaluated clinically by the Insall and Kujala score and radiographically by measuring the congruence angle, lateral patellofemoral angle, and lateral patellar translation pre- and postoperatively. Patients were classified into 2 groups: group 1 comprised 23 patients with TD greater than or equal to 3.0 mm and group 2 comprised 22 patients with TD less than 3.0 mm. A significant improvement (P=.007) in postoperative clinical scores compared with preoperative values was observed. The congruence angle improved to 11.0°±20.6° (P=.006), the lateral patellofemoral angle improved to -1.6°±7.7° (P≤.0001), and the lateral patellar translation improved to 8.7±5.3 mm (P≤.0001) postoperatively. There were 5 (11%) failure cases. No significant difference existed in the number of failure cases and clinical scores between the 2 groups. This arthroscopic medial soft tissue pullout technique showed good clinical and radiologic results for patellar instability even in the presence of mild to moderate trochlear dysplasia. However, the technique showed limited success in severe trochlear dysplasia cases.

Three-dimensional transfer of the tibial tuberosity for patellar instability with patella alta

BACKGROUND

Although patellar instability can be treated with several surgical procedures, the appropriate surgical treatment for patellar instability with patella alta has not yet been investigated. The objective of this study is to find out whether three-dimensional transfer of the tibial tuberosity elicits good knee functionality with improved patella alta and prevents further patellar dislocation.

METHODS

Twelve knees (10 patients) underwent surgery for patellar instability with patella alta from 2007 to 2011. The surgery performed was a three-dimensional transfer for the anteromedial distalization of the tibial tuberosity. Predisposing anatomical factors for patellar instability were evaluated preoperatively; femorotibial angle (FTA), patella alta (IS ratio), trochlear dysplasia (sulcus angle) and tilting angle (lateral tilt). The function of the knee was assessed before and after surgery by Lysholm and Kujala score.

RESULTS

Before surgery, the IS ratio was 1.34 ± 0.13, lateral tilt was 22.4° ± 6.5°, and the sulcus angle was 151.7° ± 8.3°, indicating patella alta, laterality, and trochlear dysplasia. After surgery, the IS ratio and lateral tilt significantly improved to 0.95 ± 0.13, and 10.6° ± 3.4°, respectively. FTA and sulcus angle were not altered. Lysholm and Kujala score improved from 63.8 to 94.7 and 67.0 to 94.1 points, respectively. Most patients displayed good outcomes except for one patient who suffered re-dislocation by hitting their knee on the floor, 2.5 years after surgery.

CONCLUSION

Three-dimensional tibial tuberosity transfer was shown to correct the patella position and result in a good clinical outcome. This method is introduced as an alternative surgery for patellar instability with patella alta.

Distal realignment (tibial tuberosity transfer)

Although tibial tuberosity (TT) transfer has for many years been the basis of many protocols for the management of patellar instability, the role of pure medial transfer in particular appears to be declining. In contrast, the greater recognition of the importance of patella alta as a predisposing factor to recurrent patellar dislocation has resulted in a resurgence in the popularity of distal TT transfer. When TT transfer is performed, the direction and amount of transfer is based on the patellar height and the lateralization of the TT relative to the trochlear groove. Patellar height is best assessed on a lateral radiograph with the knee in flexion using a ratio that uses the articular surface of the patella in relation to the height above the tibia. Assessment of lateralization of the TT relative to the trochlear groove can be made using either computed tomography or magnetic resonance imaging scans.

Modern management of patellar instability

Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

[Musculoskeletal modeling of the patellofemoral joint. Dynamic analysis of patellar tracking]

Numerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.

In vivo positioning analysis of medial patellofemoral ligament reconstruction

BACKGROUND

Several techniques have been described for reconstruction of the medial patellofemoral ligament (MPFL). The anatomical insertion of the MPFL has been defined; however, there are no reports describing the accuracy of femoral graft positioning assessed postoperatively.

PURPOSE

To analyze our femoral tunnel positioning for MPFL reconstruction in correlation with our clinical results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors reported a prospective series of 29 MPFL reconstructions with a minimum follow-up of 24 months. The tunnel positioning analysis was performed using plain radiographs and magnetic resonance imaging at 1-year follow-up.

RESULTS

Twenty-nine femoral tunnels were analyzed; 20 femoral tunnels (69%) were considered to be in good position on plain radiographs. On magnetic resonance imaging, the authors found 19 femoral tunnels (65%) in a proper location, 5 (17.5%) in a high position, and 5 in an anterior and/or high position.

CONCLUSION

The study highlights the difficulty of reproducible MPFL reconstruction. The surgical procedure continues to be improved and finding a reliable technique to anatomically place the graft remains challenging. Verifying femoral tunnel placement radiographically may be recommended during surgery.

MR imaging of patellar instability: injury patterns and assessment of risk factors

First-time patellar dislocation typically occurs with twisting knee motions, during which the medial ligamentous stabilizers rupture, and the patella strikes against the lateral femoral condyle. The typical injury pattern is a tear of the medial patellofemoral ligament (MPFL) and bone bruises of the patella and the lateral femoral condyle. Additionally, complex injuries to bone, cartilage, and ligaments may occur. The ensuing loss of medial restraint favors future patellar dislocations, especially if additional risk factors are present. Recurrent patellar dislocations usually occur in individuals with anatomic variants of the patellar stabilizers, such as trochlear dysplasia, patella alta, and lateralization of the tibial tuberosity. Magnetic resonance (MR) imaging is reliable in identifying risk factors for chronic patellar instability and in assessing knee joint damage associated with patellar dislocation. MR imaging can thus provide important information for individually tailored treatment. Patients with primary patellar dislocation without severe internal derangement who lack major risk factors can be treated conservatively. Patients with pronounced ligamentous tears or large osteochondral lesions require prompt surgery. In addition, surgical correction of anatomic variants will help reduce the potential for chronic instability. The most common procedures, in addition to MPFL reconstruction, include trochleoplasty, medialization of the tibial tuberosity, and medial capsular plication. For comprehensive assessment of patellar dislocation, a radiologist should be able to identify typical injury patterns, know standard methods to assess risk factors for patellar instability, and be familiar with surgical options.

Rehabilitation after anteromedialization of the tibial tuberosity

Various surgical procedures are currently being used to treat symptomatic patellar instability. Distal bony realignment techniques attempt to correct malalignment by shifting the site of insertion of the patellar tendon. Tibial tuberosity anteromedialization, also known as the Fulkerson osteotomy, is a process in which the tuberosity is transferred anteriorly and medially. Although this surgical technique has been well described in the literature and the results are generally reported to be very good, the operation requires a prolonged recovery period and little has been written specifically regarding postoperative rehabilitation. This article discusses the rationale and technique for anteromedialization and emphasizes the important principals and goals of rehabilitation.

MPFL reconstruction for PF instability. The soft (tissue) approach

Historically, anatomic factors have been identified that increase one's risk for episodic lateral patella dislocations. A surgical treatment algorithm has been proposed which utilizes these risk factors. This algorithm depends primarily on realignment of the bony architect. Increasingly, the soft tissue retinacular restraints have been shown to be important as an anatomic factor critical for patellofemoral stability; in particular, the medial patellofemoral ligament (MPFL) has been recognized as the essential stabilizer against lateral patella displacement. Current indications for MPFL reconstructions will be reviewed. The frequency of reconstructing the MPFL alone versus combining it with other realignment schemes in my last 30 patients will be presented.

Understanding patellofemoral pain with maltracking in the presence of joint laxity: complete 3D in vivo patellofemoral and tibiofemoral kinematics

Patellofemoral pain is widely accepted as one of the most common pathologies involving the knee, yet the etiology of this pain is still an open debate. Generalized joint laxity has been associated with patellofemoral pain, but is not often discussed as a potential source of patellar maltracking. Thus, the objective of this study was to compare the complete 6 degree of freedom patellofemoral and tibiofemoral kinematics from a group of patients diagnosed with patellofemoral pain syndrome and maltracking to those from an asymptomatic population. The following null hypotheses were tested: kinematic alterations in patellofemoral maltracking are limited to the axial plane; knee joint kinematics are the same in maltrackers with and without generalized joint laxity (defined by a clinical diagnosis of Ehlers Danlos Syndrome); and no correlations exist between tibiofemoral and patellofemoral kinematics or within patellofemoral kinematics. This study demonstrated that alterations in patellofemoral kinematics, associated with patellofemoral pain, are not limited to the axial plane, minimal correlations exist between patellofemoral and tibiofemoral kinematics, and distinct subgroups likely exist within the general population of maltrackers. Being able to identify subgroups correctly within the omnibus diagnosis of patellar maltracking is a crucial step in correctly defining the pathophysiology and the eventual treatment of these patients.

[Lateral retinacular release]

This overview of numerous studies discusses, based on short-term and long-term results, which diagnoses are indications for lateral retinacular release. No significant differences in outcome between arthroscopic and open lateral release could be documented. Isolated lateral release offers a good success rate for treating a stable patella with excessive lateral pressure. In patellar instability, the results are less favorable in long-term follow-up evaluation. Hyperlaxity with hypermobility of the patella is an absolute contraindication. Lateral release provides only temporary benefit for patellofemoral osteoarthritis. Proximal and/or distal realignment of the extensor mechanism gives better results than isolated lateral release.