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

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

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction has recently been broadly accepted as primary surgical treatment in adults. Reconstruction techniques with osseous fixation in femur cannot be used for patients with open growth plates. Operative treatment of patella instability in children therefore is a challenge and requires alternative MPFL reconstruction techniques. Limited knowledge exists concerning outcome after MPFL reconstruction in children and adolescents. This study present clinical outcome in a consecutive single clinic series of children treated with paediatric MPFL reconstruction using a soft tissue femoral fixation technique.

METHODS

Twenty-four MPFL reconstructions in 20 operated children aged 8-16 were included in the study. Indication for surgery was two or more patella dislocations. MPFL reconstruction was performed by looping the released gracilis tendon around the adductor magnus tendon insertion and through drill holes in the proximal medial patella edge. Clinical outcome was evaluated by Kujala score and NRS pain score preoperatively, at 1-year follow-up and final follow-up at 39 months. Outcome was compared with a cohort of 179 adult patients with recurrent patella instability operated with an adult MPFL reconstruction technique.

RESULTS

Kujala score improved from 61 (13) to 81 (16). NRS pain score improved from 3.0 (3.1) to 1.5 (1.3) in activity. Four patients (20%) experienced redislocation within the first postoperative year compared with 5% in an adult patient population. Five patients (25%) experienced subluxations. One patient with a redislocation was re-operated with adult MPFL reconstruction technique. Cartilage injury was seen in six patients.

CONCLUSIONS

There are clinical relevant improvements in knee function and pain after MPFL reconstruction in paediatric patients. Patella stability after MPFL reconstruction using femoral soft tissue graft fixation in paediatric patients was inferior to MPFL reconstruction using bony femoral fixation in adult patients.

LEVEL OF EVIDENCE

Case-Control study, Level III.

MRI-associated classification to evaluate the outcome after autologous reconstruction of the medial patellofemoral ligament: a preliminary study

PURPOSE

Purpose of this study was to establish and validate an MRI-associated classification to graduate postoperative results of MPFL reconstructions.

METHODS

30 autologous MPFL reconstructions of 28 patients were evaluated by two independent raters using MRI. All grafts were assigned to a novel graduation system respecting the graft's anchoring insertions, its MRI signal appearance, continuity and tension and the differentiation relating to the surrounding soft tissue.

RESULTS

All grafts could reliably be assigned to one of the subgroups by both raters. 86.6 % of the grafts could be classified A1 or B1, reflecting a correct positioning and a low to intermediate signal intensity. Only one graft had to be classified C3 (malpositioned, elongated).

CONCLUSION

We were able to establish and validate an MRI-associated classification to graduate the postoperative outcome after MPFL reconstructions. Foresighted, the presented classification might support further decision making in case of unsatisfying postoperative results.

Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph: The Importance of Anatomy in Medial Patellofemoral Ligament Reconstruction

BACKGROUND

Studies have reported methods for radiographically delineating medial patellofemoral ligament (MPFL) femoral tunnel position on a true lateral knee radiograph. However, obtaining a true lateral fluoroscopic radiograph intraoperatively can be challenging, rendering radiographic methods for tunnel positioning potentially inaccurate.

PURPOSE

To quantify the magnitude of MPFL femoral tunnel malposition that occurs on true lateral and aberrant lateral knee radiographs when using a previously reported radiographic technique for MPFL femoral tunnel localization.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten fresh-frozen cadaveric knees were dissected to expose the MPFL femoral insertion and surrounding medial knee anatomy. True lateral and aberrant lateral knee radiographs at 2.5°, 5°, and 10° off-axis were obtained with a standard mini C-arm in 4 orientations: anterior to posterior, posterior to anterior, caudal, and cephalad. A previously reported radiographic method for MPFL femoral localization was performed on all radiographs and compared in reference to the anatomic MPFL attachment center.

RESULTS

The radiographic point, as previously described, was a mean distance of 4.1 mm from the anatomic MPFL attachment on a true lateral knee radiograph. The distance between the anatomic MPFL attachment center and the radiographic point significantly increased on aberrant lateral knee radiographs with as little as 5° of rotational error in 3 of 4 orientations of rotation when a standard mini C-arm was used. This corresponded to a malposition of 7.5, 9.2, and 8.1 mm on 5°-aberrant radiographs in the anterior-posterior, posterior-anterior, and cephalad orientations, respectively (P < .005). In the same 3 orientations of rotation, MPFL tunnel malposition on the femur exceeded 5 mm on 2.5° aberrant radiographs.

CONCLUSION

The commonly utilized radiographic point, as previously described for MPFL femoral tunnel placement, results in inaccurate tunnel localization on a true lateral radiograph, and this inaccuracy is perpetuated with aberrant radiography. Aberrant lateral knee imaging of as little as 5° off-axis from true lateral has a significant effect on placement of a commonly used radiographic point relative to the anatomic MPFL femoral attachment center and results in nonanatomic MPFL tunnel placement.

CLINICAL RELEVANCE

This study demonstrates that radiographic localization of the MPFL femoral tunnel results in inaccurate tunnel placement on a true lateral radiograph, particularly when there is deviation from a true lateral fluoroscopic image, which can be difficult to obtain intraoperatively. Assessing anatomy directly intraoperatively, rather than relying solely on radiographs, may help avoid MPFL tunnel malposition.

Factors Affecting the Outcomes of Double-Bundle Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocations Evaluated by Multivariate Analysis

BACKGROUND

Many factors are involved in causing patellar instability or recurrent patellar dislocations. However, factors affecting the outcomes of anatomic medial patellofemoral ligament (MPFL) reconstruction have not been fully documented.

PURPOSE

To evaluate the rate of recurrent patellar instability after isolated MPFL reconstruction and to elucidate factors affecting the outcomes of isolated MPFL reconstruction using multivariable statistics.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 42 patients (44 knees) who underwent isolated, anatomic MPFL reconstruction using a semitendinosus autograft without any additional patellar stabilization procedures for treating recurrent patellar dislocations were included in this study. All patients were followed for more than 2 years; the mean follow-up period was 3.2 years (range, 2-9 years). Postoperative patellofemoral instability was diagnosed when the patient complained of recurrent patellar subluxations or dislocations or had a positive apprehension sign during follow-up. Preoperative radiographic findings were obtained using plain radiography and computed tomography. Femoral tunnel positions were assessed on postoperative radiographs. The strength of the relationship between postoperative patellofemoral instability and potential risk factors such as preoperative age, sex, body mass index, patellar type, sulcus angle, congruence angle, lateral tilt angle, patellar height, tibial tubercle-trochlear groove (TT-TG) distance, degree of trochlear dysplasia, and femoral bone tunnel position were evaluated by univariate and multivariate logistic regression analyses.

RESULTS

At follow-up, 2 knees had experienced a redislocation (4.5%). A positive apprehension sign was still evident in 8 knees (18.2%). Three factors, including the sulcus angle, the congruence angle, and trochlear dysplasia, were extracted by single linear regression analysis. Univariate logistic regression analysis showed that the sulcus angle (odds ratio [OR], 1.11; 95% CI, 1.01-1.22; P = .04) and trochlear dysplasia (OR, 3.04; 95% CI, 1.39-6.63; P = .01) were associated with postoperative patellofemoral instability. Trochlear dysplasia was independently associated with postoperative patellofemoral instability by multivariable logistic regression analysis (P < .05). An increased TT-TG distance exerted a significant effect on the outcomes of MPFL reconstruction, particularly in patients with type D trochlea.

CONCLUSION

Severe trochlear dysplasia is the most important predictor of residual patellofemoral instability after isolated MPFL reconstruction. In addition, an increased TT-TG distance affected the outcomes in patients with type D trochlea. Additional patellar stabilization procedures should be considered for patients with severe trochlear dysplasia and an increased TT-TG distance.

Deepening Trochleoplasty With a Thick Osteochondral Flap for Patellar Instability: Clinical and Functional Outcomes at a Mean 6-Year Follow-up

BACKGROUND

In patients with patellar instability and severe trochlear dysplasia, trochleoplasty has become increasingly used as part of its surgical management.

HYPOTHESIS

Deepening trochleoplasty for severe dysplasia in patellofemoral instability improves function and increases sports participation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 1995 and 2010, deepening trochleoplasty with a thick flap was performed in 90 patients (107 knees) with severe trochlear dysplasia. Data were collected prospectively preoperatively, at 6 weeks, and at 1-year follow-up. The patients were surveyed retrospectively to determine the clinical and functional outcomes including sports and exercise participation at a minimum of 2 years, with complete data available in 92%.

RESULTS

The average follow-up was 6 years (range, 2-19 years). The median Kujala score was 63 (interquartile range [IQR], 47-75) preoperatively, rising to 79 (IQR, 68-91) at 1-year follow-up and 84 (IQR, 73-92) at final follow-up (P < .05). Seventy-two percent were satisfied with their knee function at 1-year follow-up, rising to 83% at final follow-up (P < .0001). Sports and exercise participation increased from 36 patients (40%) preoperatively to 60 (67%) at final follow-up. The number of patients involved in competitions increased slightly from 10 (11%) to 11 (12%). Of those sports that involved twisting (e.g., soccer, cricket, badminton), the number of patients participating increased from 16 (18%) to 22 (24%), whereas in nontwisting sports (e.g., running, swimming, cycling), it increased from 24 (27%) to 47 (52%), of whom 12 (16%) used walking as exercise. Two patients who had undergone medial patellofemoral ligament (MPFL) reconstruction as the index operation needed the MPFL revised, and a further 8 patients needed MPFL reconstruction subsequently for instability symptoms and a mediolateral glide in extension of more than 2 quadrants' displacement. At final follow-up, no patient had mechanical patellofemoral instability.

CONCLUSION

Deepening trochleoplasty with a thick flap improves clinical and functional outcomes for patients with symptomatic patellar instability with severe trochlear dysplasia. These results improve over time and beyond 1-year clinical follow-up. However, trochleoplasty does not lead to a significant improvement in sports participation at a competitive level. It does improve patient participation in sports and exercise, principally in nontwisting sports activities.

Patellofemoral Pressure Changes After Static and Dynamic Medial Patellofemoral Ligament Reconstructions

BACKGROUND

Reconstructing the medial patellofemoral ligament (MPFL) has become a key procedure for stabilizing the patella. Different techniques to reconstruct the MPFL have been described: static techniques in which the graft is fixed rigidly to the bone or dynamic techniques with soft tissue fixation. Static MPFL reconstruction is most commonly used. However, dynamic reconstruction deforms more easily and presumably functions more like the native MPFL.

PURPOSE/HYPOTHESIS

The aim of the study was to evaluate the effect of the different MPFL fixation techniques on patellofemoral pressures compared with the native situation. The hypothesis was that dynamic reconstruction would result in patellofemoral pressures closer to those generated in an intact knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven fresh-frozen knee specimens were tested in an in vitro knee joint loading apparatus. Tekscan pressure-sensitive films fixed to the retropatellar cartilage measured mean patellofemoral and peak pressures, contact area, and location of the center of force (COF) at fixed flexion angles from 0° to 110°. Four different conditions were tested: intact, dynamic, partial dynamic, and static MPFL reconstruction. Data were analyzed using linear mixed models.

RESULTS

Static MPFL reconstruction resulted in higher peak and mean pressures from 60° to 110° of flexion (P < .001). There were no differences in pressure between the 2 different dynamic reconstructions and the intact situation (P > .05). The COF in the static reconstruction group moved more medially on the patella from 50° to 110° of flexion compared with the other conditions. The contact area showed no significant differences between the test conditions.

CONCLUSION

After static MPFL reconstruction, the patellofemoral pressures in flexion angles from 60° to 110° were 3 to 5 times higher than those in the intact situation. The pressures after dynamic MPFL reconstruction were similar as compared with those in the intact situation, and therefore, dynamic MPFL reconstruction could be a safer option than static reconstruction for stabilizing the patella.

CLINICAL RELEVANCE

This study showed that static MPFL reconstruction results in higher patellofemoral pressures and thus enhances the chance of osteoarthritis in the long term, while dynamic reconstruction results in more normal pressures.

Are meniscal tears and articular cartilage injury predictive of inferior patient outcome after surgical reconstruction for the dislocated knee?

PURPOSE

A paucity of data exists on the effects of articular cartilage and meniscal injury in the setting of knee dislocations. The purpose of this study is to determine whether concomitant intra-articular injuries at the time of multiligament reconstruction for knee dislocation are associated with inferior outcomes.

METHODS

The records of patients who underwent surgical treatment for multiligament knee injury between 1992 and 2012 were retrospectively reviewed. Patients included had a PCL-based multiligament knee injury or a minimum of three disrupted ligaments, both indicative of knee dislocation. A logistic regression model was used to determine whether articular cartilage injuries (grade 2 involving ≥50 % of the condylar width or greater, or any grade III/IV lesions) and meniscus tears are predictors of IKDC outcome scores collected at a minimum of 2 years postoperatively.

RESULTS

Of the 121 patients who met inclusion criteria, 2-year minimum follow-up was available on 95 patients (79 %). The cohort was 77 % male and had a median age of 32 years (16-62) at the time of surgery and was followed for an average of 6 years. Articular cartilage injury was present in 40 % of knees: medial femoral condyle (20 %); medial tibial plateau (9 %); lateral femoral condyle (5 %); lateral tibial plateau (4 %); patella (18 %); trochlear (5 %). Meniscal injury was present in 56 % of patients (isolated medial, 22 %; isolated lateral, 22 %; combined, 12 %). IKDC scores were significantly lower for patients with any cartilage damage (p = 0.03), combined medial and lateral meniscus tears (p = 0.02), medial-sided articular cartilage damage (p = 0.03), medial femoral condyle (p = 0.04) and trochlear (p = 0.03) lesions.

CONCLUSION

Articular cartilage damage and meniscus tears are frequently associated with a knee dislocation. This study showed IKDC scores were significantly lower for patients with cartilage damage or combined medial and lateral meniscus tears at mid-term follow-up of 6 years.

LEVEL OF EVIDENCE

IV.

Medial Patellofemoral Ligament Reconstruction: A Comprehensive Review

It has been suggested that in the majority of patellar dislocation cases, the medial patellofemoral ligament (MPFL) is disrupted with a high recurrence rate especially in female patients. Although MPFL tear is not the primary cause of instability, MPFL reconstruction is effective for stabilizing the knee and may alone prevent lateral patellar dislocation. There is limited but growing evidence that MPFL reconstruction for patellofemoral instability leads to excellent functional outcomes. Growing awareness of the biomechanical contribution of the MPFL has led to an upsurge in the publication of techniques and trials dealing with reconstructive techniques, warranting a review that includes the most recent evidence. The aim of this article was to review and summarize the recent literatures concerning MPFL reconstruction and provide a comprehensive review of previous studies ranging from basic science to current surgical techniques and results.

Results of isolated lateral retinacular reconstruction for iatrogenic medial patellar instability

PURPOSE

The aim of this study was to assess the outcomes of an isolated lateral retinaculum reconstruction for iatrogenic medial patellar instability (IMPI) in patients with continued pain after failed lateral retinacular release (LRR), including associated psychometric analysis.

METHODS

Pain was assessed using the visual analog scale (VAS) and disability was determined with the Lysholm scale. Psychological variables such as anxiety, depression, catastrophizing, and fear-of-movement beliefs were studied by using self-administered psychometric questionnaires.

RESULTS

All 17 patients (13 women and 4 men) in this retrospective study had undergone LRR previously for anterior knee pain or lateral patellar instability. Four patients had undergone LRR plus proximal (Insall) realignment, and one had undergone LRR plus a medial tibial tubercle transfer. After their procedures, all had disabling symptoms. All patients underwent reconstructive surgery for IMPI. At a minimum follow-up of 2 years (range, 2 to 8 years), the mean preoperative VAS score was 7.6 (range, 5 to 9) and improved to 1.9 (range, 0 to 8) at the time of final follow-up (P < .001). The mean preoperative Lysholm score was 36.4 (range, 20 to 55), and the knee was described as bad (<65 points) in all cases. Postoperatively, it improved to 86.1 (range, 70 to 94) at final follow-up (P < .001). Before surgery, 4 patients (24%) had the clinical criteria for depression, 10 (59%) had anxiety, 7 (41%) had "catastrophizing" ideas concerning pain, and all (100%) had kinesiophobia (fear of movement). After surgery, none of the patients had depression or anxiety, none had catastrophizing ideation, and only 53% had kinesiophobia.

CONCLUSIONS

Reconstruction of the deep transverse layer of the lateral retinaculum (LR) using a central strip of the iliotibial band for IMPI in patients with continued pain after failed LRR can successfully treat these severely disabled patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.