Medial patellofemoral ligament reconstruction in patients with lateral patellar instability and trochlear dysplasia

Reconstruction of the medial patellofemoral ligament by means of the anatomical double-bundle technique using metal anchors

Objective

To evaluate double-bundle reconstruction of the medial patellofemoral ligament (MPFL) using a graft from the semitendinosus tendon and fixation with metal anchors over the medium term.

Methods

This was a prospective cross-sectional study. After approval from the research ethics committee, 31 patients with patellofemoral instability who underwent MPFL reconstruction by means of the anatomical double-bundle technique, with fixation using metal anchors, were analyzed between May 2010 and January 2015. To evaluate the effectiveness of the MPFL reconstruction surgery, the Kujala scale and the Tegner–Lysholm score were assessed before the procedure and one year afterwards, along with clinical data such as pain levels, range of motion and J sign. The data were tabulated in the Excel^® software and were analyzed using the SPSS Statistics^® software, version 21. The statistical analysis was performed using the Wilcoxon T test and the McNemar test.

Results

The mean preoperative score from the Kujala test was 45.64 ± 1.24 and the postoperative score was 94.03 ± 0.79 (p < 0.001). The preoperative Tegner–Lysholm score was 40.51 ± 1.61 and the postoperative score was 91.64 ± 0.79 (p < 0.001). The preoperative range of motion was 125.96 ± 2.11 and the postoperative range was 138.38 ± 1.49 (p < 0.05).

Conclusion

MPFL reconstruction by means of the anatomical double-bundle technique is easily reproducible, without episodes of recurrence, with satisfactory results regarding restoration of stability and function of the patellofemoral joint.

A new classification system of patellar instability and patellar maltracking

To date there is no classification of patellar dislocations considering clinical and radiological pathologies. As a result many studies mingle the dislocation's underlying pathologies, so that there are no consistent therapy recommendations. It is this article's objective to introduce a patellar dislocation classification based on the current literature to allow for the application of a structured diagnosis and treatment algorithm. The classification is based on instability criteria as well as on clinical and radiological analyses of maltracking and on loss of patellar tracking. There are five types of patellar instability and maltracking. The rare type 1 is a simple (traumatic) patellar dislocation without maltracking and instability with a low risk of redislocation. Type 2 has a high risk of redislocation after primary dislocation; there is no maltracking. Here, a stabilising operation (in most cases MPFL reconstruction) is indicated and sufficient. Type 3 shows both instability and maltracking. Maltracking is mainly caused by: (a) soft tissue contracture, (b) patella alta, (c) pathological tibial tuberosity-trochlea groove distance, (d) valgus deviations and (e) torsional deformities. Stabilisation by means of isolated MPFL reconstruction is not sufficient in these types and additional osseous corrective surgeries are required to achieve physiological patellar tracking and to prevent redislocation. Type 4 features a highly unstable "floating patella" with complete loss of tracking caused by severe trochlear dysplasia. Therapy of choice is trochleoplasty, and if necessary combined with bony and soft-tissue procedures. Type 5 shows a patellar maltracking without instability. Maltracking can only be fixed by means of corrective osteotomy. The classification is referenced to current literature and each type is introduced by a case example. The resulting treatment consequence 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.

Reconstruction of medial patello-femoral ligament: Comparison of two surgical techniques

The medial patello-femoral ligament is considered the most important passive patellar stabilizer and its proper functionality is essential for the patello-femoral joint stability. In this work, 18 human knees were randomly divided into two groups and reconstructed through two different surgical techniques: the "Through tunnel tendon" and the "Double converging tunnel" reconstructions. Subsequently, the samples were mechanically tested to evaluate the structural properties of reconstructed femur-MPFL-Patella complex (rFMPC). Particular attention was given to maintain the anatomical orientation between the patella and the graft. Both procedures showed lower stiffness and higher ultimate strain and absorbed energy compared to the native MPFL, but the advantages of the double converging tunnel technique are related to the restoration of the native MPFL sail-shape, to a better stress distribution on the patella, to the use of a single interference screw as fixation device and to the simplicity, rapidity and cost-effectivity of the surgical procedure. The evaluation of the structural properties of rMPFL is fundamental to evaluate the adequacy of the different techniques to restore the physiological structural properties of the native MPFL.

Recovery of gait pattern after medial patellofemoral ligament reconstruction for objective patellar instability

Gait pattern alterations were previously reported in association with objective patellar instability (OPI). Gait pattern comparison between a series of patients having undergone medial patellofemoral ligament (MPFL) reconstruction and a sample of control subjects. Thirty patients at 6 months postoperatively after MPFL reconstruction and thirty control subjects were enrolled in the study for a clinical and biomechanical assessment including gait analysis at three selected walking rates using the GAITRite(®) system. The mean raw IKDC score was 73 (± 19), and the mean Kujala knee function was 84 (± 17.5). The study of gait did not demonstrate any significant difference between the two groups at a normal and fast walking rate. At a 10 km/h running speed, the single-support phase was significantly shortened by a mean 2.33% (p < 0.05), the swing phase by a mean 2.64% (p < 0.05) and the double-support phase by a mean 3.49% (p < 0.05) on the operated side. MPFL reconstruction reported good midterm functional and clinical results in the management of OPI. At 6 months postoperatively, the patient gait pattern was similar to that observed in healthy subjects at a normal and fast walking speed. However, our study revealed persistent gait abnormalities at a 10 km/h running speed. These gait alterations seemed to be related to the ligament reconstruction in itself due to the higher strain applied on the reconstructed MPFL during running cycle (10 km/h). Level of evidence IV.

"Basket weave technique" for medial patellofemoral ligament reconstruction: Clinical outcome of a prospective study

BACKGROUND

Bone tunneling and implants with rigid fixations for medial patellofemoral ligament (MPFL) reconstruction are known to compromise results and are avoidable, especially in skeletally immature subjects. This study was to assess if these deficiencies were overcome with the technique devised by the author which avoids implants and bone tunnels. Results were assessed for complication rate and outcome.

MATERIALS AND METHODS

Fifty six knees of recurrent lateral patellar dislocation were treated in the past 49 months by MPFL reconstruction. Thirty nine were female and 17 male knees. The mean age was 20.6 years (range 9-48 years). Mean followup was 26 months. Five knees had previously failed stabilization procedures. Thirty one cases had Dejours Type A or B and 12 had Type C trochlear dysplasia. Arthroscopy was performed for associated injuries and loose bodies. Seven knees required loose body removal. Five knees underwent lateral retinacular release. Four knees had tibial tuberosity transfer. One knee had an associated anterior cruciate ligament reconstruction. An anatomical MPFL reconstruction was performed using hamstring autograft without the need for intraoperative fluoroscopy. Only soft tissue fixation was necessary with this newly devised technique and suturing. A rapid rehabilitation protocol was implemented with monthly followup until normalcy and 6 monthly thereafter.

RESULTS

All achieved full range of motion and normal mediolateral stability. There was no recurrence of dislocation. No major surgery related complications. One patella fracture at 8 months was due to a fall developed terminal restriction of flexion. Those in sports could return to their sporting activities (Tegner 1-9). Cases with osteochondral fractures had occasional pain that subsided in 1 year. Mean Kujala score improved from 64.3 to 99.69 with KOOS score near normal in all.

CONCLUSION

This new method of MPFL reconstruction gives excellent results. It avoids complications related to bone tunneling and implants. It is a safe, effective, reliable and reproducible technique.

Classification of Lateral Patellar Instability in Children and Adolescents

There is significant heterogeneity in the literature related to the causes and treatment of patellar instability. To address the multifactorial issue of patellar instability, the first task is to classify the instability pattern. Once a classification system is developed, future studies can differentiate between treatment recommendations and outcomes for each instability pattern. Existing classification systems do not include the entire spectrum of patellar instability patterns. The aim of this article is to review the nomenclature and existing patellar instability classification systems and analyze the different patterns into a comprehensive system.

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.

MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION TO TREAT RECURRENT PATELLAR DISLOCATION

OBJECTIVE

To present a new technique for reconstruction of the medial patellofemoral ligament (MPFL) in patients with recurrent patellar dislocation and to evaluate the clinical findings from this.

METHODS

Between January 2007 and January 2008, 23 patients underwent reconstruction of the MPFL with a free graft from the semitendinosus tendon. After a minimum of 24 months of follow-up, 22 patients were evaluated using the Kujala and Lysholm clinical protocols.

RESULTS

The mean follow up was 26.2 months. According to the Lysholm protocol, the patients had a mean score of 53.72 points preoperatively and 93.36 points postoperatively (p = 0.000006). According to the Kujala protocol, the mean score was 59.81 points preoperatively and 83.54 points postoperatively (p = 0.002173).

CONCLUSION

Reconstruction of the medial patellofemoral ligament using the proposed technique showed excellent results over the short term, when evaluated by means of clinical protocols.

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.

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.

Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability Using a Gracilis Autograft without Bone Tunnel

Background

Several tendon graft and fixation methods have been introduced in medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar dislocation. The purpose of this study was to evaluate the results of MPFL reconstruction using a gracilis autograft fixation without bone tunnel in patients with recurrent patellar instability.

Methods

Nine patients (four males and five females) diagnosed with recurrent patellar instability from July 2009 to January 2013 and had MPFL reconstruction using a gracilis autograft were included. The average age of the patients was 24.6 years (range, 13 to 48 years), and the average follow-up period was 19.3 months (range, 12 to 30 months). For every patient, femoral attachment was fixed using suture anchors securing the patella by suturing the periosteum and surrounding soft tissue. Clinical evaluation included the Kujala, Lysholm, and Tegner scores; in addition, patients were examined for any complication including recurrent dislocation. The congruence angle and patella alta were assessed radiologically before and after surgery.

Results

The Kujala score improved from an average of 42.7 ± 8.4 before surgery to 79.6 ± 13.6 (p = 0.008) at final follow-up; the Lysholm score improved from 45.8 ± 5.7 to 82.0 ± 10.5 (p = 0.008); and the Tegner score improved from 2.8 ± 0.8 to 5.6 ± 1.5 (p = 0.007). The Insall-Salvati ratio changed from 1.16 ± 0.1 (range, 0.94 to 1.35) before surgery to 1.14 ± 0.1 (range, 0.96 to 1.29; p = 0.233) at the final follow-up without significance. The congruence angle significantly improved from 26.5° ± 10.6° (range, 12° to 43°) before surgery to -4.0° ± 4.3° (range, -12° to 5°; p = 0.008) at final follow-up. Subluxation was observed in one patient and hemarthrosis occurred in another patient 2 years after surgery, but these patients were asymptomatic.

Conclusions

We achieved good results with a patellar fixation technique in MPFL reconstruction using a gracilis autograft employing soft tissue suturing in patients with recurrent patellar dislocation.

BIOMECHANICAL ACCESS METHOD FOR ANALYZING ISOMETRICITY IN RECONSTRUCTING THE MEDIAL PATELLOFEMORAL LIGAMENT

OBJECTIVE

To present a biomechanical device for evaluating medial patellofemoral ligament (MPFL) reconstruction and its isometricity.

METHODS

An accessible biomechanical method that allowed application of physiological and non-physiological forces to the knee using a mechanical arm and application of weights and counterweights was developed, so as to enable many different evaluations and have a very accurate measurement system for distances between different structures, for analysis on experiments. This article describes the assembly of this system, and suggests some practical applications. Six cadaver knees were studied. The knees were prepared in a testing machine developed at the Biomechanics Laboratory of IOT-HCFMUSP, which allowed dynamic evaluation of patellar behavior, with quantification of patellar lateralization between 0° and 120°. The differences between the distances found with and without load applied to the patella were grouped according to the graft fixation angle (0°, 30°, 60° or 90°) and knee position (intact, damaged or reconstructed).

RESULTS

There was a tendency for smaller lateral displacement to occur at fixation angles greater than 30 degrees of flexion, especially between the angles of 45° and 60° degrees of flexion, after the reconstruction. For the other angles, there was no statistical significance.

CONCLUSION

The method developed is a useful tool for studies on the patellofemoral joint and the MPFL, and has a very accurate measurement system for distances between different structures. It can be used in institutions with fewer resources available.

Isolated reconstruction of the medial patellofemoral ligament with autologous quadriceps tendon

Background

Since the role of the medial patellofemoral ligament (MPFL) as the primary soft-tissue restraint against lateral patellar translation has been recognized, several different reconstruction procedures for the treatment of patellar instability have been proposed over recent years. Many of these techniques require bony procedures and hardware fixation at the patellar and femoral side, leading to complications as described previously in the literature. The purpose of the present study is to describe the technique of isolated MPFL reconstruction using the quadriceps tendon and report the results at a mean follow-up of 38 months. The hypothesis is that this technique, not requiring drilling of bone tunnels on the patellar and femoral side, may be a "simple and safe" mean to manage patellar instability, giving good clinical results with low complication rate in selected patients with normal osseous anatomy.

Materials and methods

Sixteen consecutive patients (9 male, 7 female; mean age 22 years) with chronic patellar instability underwent medial patellofemoral reconstruction with the superficial layer of the quadriceps tendon. All the patients were evaluated preoperatively and postoperatively by physical examination and subjectively with Kujala and Lysholm scores.

Results

The average follow-up was 38 months (range 28–48 months). No recurrent episodes of dislocation or subluxation and no complications occurred. The mean Kujala score increased from 35.8 preoperatively to 88.8 postoperatively and the Lysholm score improved from 43.3 preoperatively to 89.3 postoperatively.

Conclusions

Isolated MPFL reconstruction using an autologous quadriceps tendon and not requiring bone tunnels, may be a safe, simple and effective procedure for the treatment of patellar instability without complications such as patellar fracture as reported by clinical studies using hamstring grafts. For the same reason it may also be indicated in skeletally immature patients.

Level of evidence

Level IV.

The ability of medial patellofemoral ligament reconstruction to correct patellar kinematics and contact mechanics in the presence of a lateralized tibial tubercle

BACKGROUND

Tibial tubercle (TT) transfer and medial patellofemoral ligament (MPFL) reconstruction are used after patellar dislocations. However, there is no objective evidence to guide surgical decision making, such as the ability of MPFL reconstruction to restore normal behavior in the presence of a lateralized TT.

HYPOTHESIS

MPFL reconstruction will only restore joint contact mechanics and patellar kinematics for TT-trochlear groove (TG) distances up to an identifiable limit.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric knees (mean TT-TG distance, 10.4 mm) were placed on a testing rig. Individual quadriceps heads and the iliotibial band were loaded with 205 N in physiological directions using a weighted pulley system. Patellofemoral contact pressures and patellar tracking were measured at 0°, 10°, 20°, 30°, 60°, and 90° of flexion using pressure-sensitive film and an optical tracking system. The MPFL attachments were marked. TT osteotomy was performed, and a metal T-plate was fixed to the anterior tibia with holes at 5-mm intervals for TT fixation. The anatomic TT position was restored after plate insertion. The TT was lateralized in 5-mm intervals up to 15 mm, with pressure and tracking measurements recorded. The MPFL was transected and all measurements repeated before and after MPFL reconstruction using a double-stranded gracilis tendon graft. Data were analyzed using repeated-measures ANOVA, Bonferroni post hoc analysis, and paired t tests.

RESULTS

MPFL transection significantly elevated lateral patellar tilt and translation and reduced mean medial contact pressures during early knee flexion. These effects increased significantly with TT lateralization. MPFL reconstruction restored patellar translation and mean medial contact pressures to the intact state when the TT was in anatomic or 5-mm lateralized positions. However, these were not restored when the TT was lateralized by 10 mm or 15 mm. Patellar tilt was restored after 5-mm TT lateralization but not after 10-mm or 15-mm lateralization.

CONCLUSION

Considering the mean TT-TG distance in this study (10.4 mm), findings suggest that in patients with TT-TG distances up to 15 mm, patellofemoral kinematics and contact mechanics can be restored with MPFL reconstruction. However, for TT-TG distances greater than 15 mm, more aggressive surgery such as TT transfer may be indicated.

CLINICAL RELEVANCE

This provides guidance to surgeons as to the threshold at which MPFL reconstruction may satisfactorily restore patellofemoral mechanics, beyond which more invasive surgery such as TT transfer may be indicated.

Patellar instability factors in isolated medial patellofemoral ligament reconstructions--what does the literature tell us? A systematic review

BACKGROUND

Many studies have demonstrated good results after medial patellofemoral ligament (MPFL) reconstruction for patients with patellar instability. The applicability of published studies to the clinical decision-making process for the individual patient with patellar instability, however, is not well elucidated.

HYPOTHESIS

There is inconsistency in the reporting of preoperative and postoperative variables, which limits the applicability of current studies to patients with patellar instability.

STUDY DESIGN

Systematic review.

METHODS

A systematic review of the literature was conducted using the search term medial patellofemoral ligament reconstruction to identify studies with cohorts of patients with isolated MPFL reconstruction. A combination of inclusion and exclusion criteria resulted in 24 studies being reviewed for a variety of preoperative demographics, physical examination findings, and imaging findings, as well as postoperative outcomes, including redislocation and responses to subjective questionnaires.

RESULTS

A physical examination of lateral patellar translation was reported in 42% of studies, by reporting an apprehension sign (n = 9), reporting quadrant translation (n = 7), or both. For patellar instability factors on imaging, patellar height was reported as a preoperative variable in 75% of studies, and trochlear dysplasia was reported in 83% of studies. The tibial tubercle-trochlear groove distance was reported as a preoperative variable in 42% of studies. The rate of redislocation after index surgery was reported in 92% of studies. Patient-related outcome measures were reported in all of the studies; the Kujala score was the most common. A homogeneous population was selected as part of the authors' surgical indications for "isolated" MPFL in 67% of studies, and a heterogeneous population was selected in 33% of studies.

CONCLUSION

Current literature on MPFL reconstruction contains diverse methods of recording preoperative and postoperative variables. Most studies report on a homogeneous population, with inconsistent applicability to the broad spectrum of patients with patellar instability. Outcomes reporting in our current literature needs more clarity and consistency regarding reporting methodology to be of value for the treating clinician.

Widespread Implementation of Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability Maintains Functional Outcomes at Midterm to Long-Term Follow-up While Decreasing Complication Rates: A Systematic Review

PURPOSE

Our primary purpose was to evaluate whether complications have increased or functional outcomes have changed as medial patellofemoral ligament (MPFL) reconstruction has been adopted by more surgeons at more institutions over recent years. Our secondary purpose was to further define the complication profile of MPFL reconstruction.

METHODS

A systematic review of the literature was performed on January 12, 2014, using the keywords "medial patellofemoral ligament reconstruction," "patellar instability reconstruction," "patellofemoral ligament reconstruction," and "MPFL." Articles meeting our inclusion criteria were reviewed. Outcome measures, functional failures, complications, graft choice, and surgical technique were recorded and analyzed.

RESULTS

Thirty-four articles met our exclusion and inclusion criteria and were reviewed. Nineteen articles were "new" additions to the literature, whereas 15 had previously been reported on in prior analyses ("old"). The 19 new articles reported a statistically significant decrease in functional failure rates, from 9.55% in older studies to 4.77% in more recent studies (P < .001). The major complication rate dropped from 2.01% to 0.46% in the newer studies (P = .005), and the minor complication rate decreased from 6.53% to 4.00% (P = .06). Postoperative Kujala scores did not show a statistically significant change between newer and older publications (89.0 [SD, 3.7] and 89.4 [SD, 4.9], respectively; P = .55). Comparing results by fixation type, as well as by graft choice, showed no statistically significant differences in terms of outcomes or complication profile.

CONCLUSIONS

With nearly twice the number of medical centers performing reconstruction of the MPFL and outcomes reported on nearly double the number of patients in recent years, functional outcomes remain favorable as complication and failure profiles are improving. Furthermore, despite a wide array of fixation techniques, as well as multiple options for graft constructs, there are no statistically or clinically significant differences in functional outcomes over time. This finding highlights the efficacy and adoptability of MPFL reconstruction for the treatment of recurrent patellar instability.

LEVEL OF EVIDENCE

Level IV, systematic review of mixed-level studies.

Sulcus deepening trochleoplasty for patellofemoral instability: A series of 34 cases after 15 years postoperative follow-up

INTRODUCTION

Trochlear dysplasia is one of the main elements of patellofemoral instability. Although correction by trochleoplasty seems logical, the long-term outcome of this procedure is unknown and the progression to osteoarthritis has not been clarified. Thus, we performed a retrospective study of a series of sulcus deepening trochleoplasties with a 15-year follow-up whose goal was to (1) evaluate the long-term clinical outcome and radiological rate of osteoarthritis, and (2) define the results in relation to the type of instability and the grade of dysplasia.

HYPOTHESIS

Sulcus deepening trochleoplasty is an effective procedure to stabilize the patellofemoral joint that does not increase the risk of osteoarthritis.

PATIENTS AND METHODS

This retrospective study analyzed 34 sulcus deepening trochleoplasties based on clinical scores (IKS, Lille, Kujala and Oxford scores) and radiological results (stage of osteoarthritis according to the Iwano score) after a mean follow-up of 15 years (12-19 years). An Insall procedure was systematically associated with an anterior tibial tubercle transfer in 17 cases (7 prior tibial transfers).

RESULTS

No recurrent objective instability was observed. Seven knees had additional surgery after a mean follow-up of 7 years (2-16): 7 underwent conversion to total knee arthroplasty because of progression of osteoarthritis and one knee had tibial tubercle transfer for pain and episodes of the knee giving way. The mean Lille, Kujala and IKS scores increased from 53.3 (30-92), 55 (13-75) and 127 (54-184) to 61.5 (25-93), 76 (51-94) and 152.4 (66-200) respectively between preoperative and follow-up assessment (P<0.05) (revisions included). Functional outcome was significantly better for dysplasia with supratrochlear spurs (IKS score 168 [127-200] versus 153 [98-198] and Kujula score 81.5 [51-98] versus 76 [51-94] [P<0.05]). Patients were satisfied in 65% of the cases and the total mean Oxford score was 24.1/60 (12-45 points). Occasional pain was present in 53% of the cases. The trochlear prominence decreased from 4.9 mm (3-9 mm) to -1.2mm (-7-4mm). Ten cases of preoperative patellofemoral osteoarthritis were identified, but none with>Iwano 2, while osteoarthritis was present in 33/34 cases at the final follow-up with 20 cases>Iwano 2 (65%).

DISCUSSION

Sulcus deepening trochleoplasty corrects patellofemoral stability even in patients with severe dysplasia and the long-term functional outcome is better in this group. It does not prevent patellofemoral osteoarthritis. It should be limited to severe dysplasia with supratrochlear spurs and associated with procedures to realign the extensor apparatus.

Anatomic reconstruction of the medial patellofemoral ligament using the fascia lata as an autograft

The medial patellofemoral ligament (MPFL) ensures stability of the patella against lateral forces. In cases of recurrent lateral patellar luxation, surgical reconstruction of the MPFL has an important role in treating lateral patellar instability. Several biomechanical studies have presented valuable pieces of information about various techniques for re-creating this medial patellofemoral complex mainly using the gracilis tendon as an autograft. However, with the increasing number of MPFL reconstructions, there are also an increasing number of patients requiring revision MPFL reconstruction. Therefore alternative graft options may become more relevant. Furthermore, the gracilis tendon as a tubular graft may not be able to fully restore patellofemoral kinematics compared with the native MPFL. This article introduces a surgical technique using the fascia lata as an alternative graft option for the anatomic reconstruction of the MPFL.

Troubleshooting the Femoral Attachment During Medial Patellofemoral Ligament Reconstruction: Location, Location, Location

The medial patellofemoral ligament (MPFL) has been recognized as an important soft tissue restraint in preventing lateral patellar translation. As many patients with acute or chronic patellar instability will have a deficient MPFL, reconstruction of this ligament is becoming more common. Appropriately, significant research has been undertaken regarding graft biomechanics and techniques, as intraoperative errors in graft placement often result in poor patient outcomes. Although the research has not answered all of the dilemmas encountered during reconstruction, publications consistently emphasize the importance of re-establishing an anatomic femoral attachment. The purpose of this study was to briefly review the current literature on MPFL reconstruction. Graft selection and patellar graft attachment and fixation are discussed, but the main focus is the femoral attachment as this is where most errors are seen and, unfortunately, where getting it right appears to matter the most. Using a sawbones knee model, the concepts of an MPFL graft that is “high and tight” or “low and loose” are presented, with the goal of providing physicians with intraoperative tools to adjust an incorrectly placed femoral MPFL attachment. This model is also used to justify the recommendation of graft fixation in 30° to 45° of knee flexion.

Selective hemiepiphyseodesis for patellar instability with associated genu valgum

BACKGROUND/AIMS

Patellar instability limits activity and promotes arthritis. Correcting genu valgum with selective hemiepiphyseodesis can treat patellar instability.

METHODS

We retrospectively reviewed 26 knees with patellar instability and associated genu valgum that underwent hemiepiphyseodesis.

RESULTS

Average anatomic lateral distal femoral angle (aLDFA) significantly corrected. Symptoms improved in all patients. All competitive athletes returned to sports. One complication occurred.

CONCLUSIONS

In genu valgum, the patella seeks an abnormal mechanical axis, resulting in patellar instability. By correcting the mechanical axis with hemiepiphyseodesis, patellar instability symptoms improve and patients return to sports. Complications are rare. Selective hemiepiphyseodesis is recommended when treating patellar instability with associated genu valgum.

MPFL reconstruction: technique and results

Patellar instability is a common problem, and medial patellofemoral ligament (MPFL) injury is inherent with traumatic patellar dislocations. Initial nonoperative management is focused on reconditioning and strengthening the dynamic stabilizers of the patella. For those patients who progress to recurrent instability, further investigation into the predisposing factors is required. MPFL reconstruction is indicated in patients with recurrent instability and insufficient medial restraint due to MPFL injury. A technique of MPFL reconstruction is outlined. This procedure may also be performed in combination with other realignment procedures.

Reconstruction of the medial patellofemoral ligament: Evaluation of the clinical results of autografts versus allografts

OBJECTIVE

The purpose of the study was to evaluate the functional results after medial patellofemoral ligament (MPFL) reconstruction in patients using auto- and allograft.

PATIENTS AND METHODS

A retrospective study was conducted on 28 patients with recurrent patellar dislocation, with 13 patients (13 knees) undergoing MPFL reconstruction with hamstring autograft, and 15 patients (16 knees) with reconstruction surgery with allograft. The total group included 13 males and 15 females, with an age range of 15 to 38 years. The graft-related morbidity was studied and a clinical assessment was performed using the pre- and postoperative Kujala score. Associated complications were reported for each group. All the patients had more than 12 months of follow up.

RESULTS

No recurrent dislocations or graft related complications were reported in either group. The post-operative Kujala subjective knee score was 89.2 in the autograft group, and 92.6 in the allograft group (p >.05). One patient in the allograft group received a revision surgery due to poor positioning of anchors. Another patient in the allograft group had non-displaced patella fracture related to the bone tunnels and another patient had flexion deficit and needed mobilization under anesthesia.

CONCLUSION

There were no significant differences between both groups, and the results were comparable.

Combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament for patients with recurrent patella dislocation and trochlear dysplasia

PURPOSE

Prospectively, a consecutive group of patients troubled by recurrent patella dislocation and trochlear dysplasia has been followed after a combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament. The purpose of this follow-up study is to report the clinical results.

METHODS

Indications for combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament were two or more patellar dislocations with a persistent apprehension sign above 20° of flexion and trochlear dysplasia grade B or more. Prospectively, the Tegner, Kujala and KOOS scores were recorded. Thirty-one consecutive patients (37 knees), 21 women and 10 men, with a median age of 19 (12-39) underwent the procedure.

RESULTS

Results were obtained for 29 knees with a minimum of 12-month follow-up (average 29 months; range 12-57). No complications, redislocations or arthrofibrosis have been recorded. Five patients needed further surgery. The median pre- and postoperative scores (range) are as follows: Kujala 64 (12-90) to 95 (47-100); Tegner 4 (1-6) to 6 (4-9); KOOS score pain 86-94; symptoms 82-86; ADL 91-99; sport 40-86; QDL 25-81. No significant correlation was found with respect to the results and recorded parameters. Significant improvement for all of the scores was observed (p<0.001).

CONCLUSIONS

The use of arthroscopic deepening trochleoplasty in combination with reconstruction of the medial patellofemoral ligament was found to be a safe and reproducible procedure. Considering the stability achieved, the knee scores and the patient's level of satisfaction, the results are encouraging.

LEVEL OF EVIDENCE

Prospective consecutive case series, with evaluation of confounding factor. No control group, Level IV.

Clinical outcome after medial patellofemoral ligament reconstruction and autologous chondrocyte implantation following recurrent patella dislocation

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction is a well-established treatment option in recurrent patella dislocation. The combination with associated retropatellar cartilage lesions are severe injuries and very difficult to treat. The purpose of this study was to evaluate our clinical results of MPFL reconstruction and autologous chondrocyte implantation (ACI).

METHODS

Thirteen patients with recurrent patella dislocation were treated with a combination of MPFL reconstruction and ACI at our institution between 2010 and 2014. All patients had at least 2 patella dislocations. The posttraumatic cartilage lesions were grade IV according to the ICRS and were localized retropatellar in 8 cases and at the lateral femoral condyle in 2 cases. The mean defect size was 7.2±3.5 cm2 (3-12 cm2). Subjective and objective scores were assessed before surgery and at f/u, as well as radiologic parameters and cartilage status on magnetic resonance imaging (MRI).

RESULTS

Ten patients (5 male, 5 female) with a mean follow-up of 2 years (minimum 1 year to 4 years) were enrolled in the study. At latest clinical follow-up, all patients had a stable patella with no signs of instability and all patients showed improved subjective and objective scores. Lysholm score increased to 74.1±18.7 (48-99), KOOS score to 74.4±16.9 (57-95), IKDC subjective to 63.9±22.1 (34-93) and Kujala score to 73.8±25.1 (50-100). The post-operative modified MOCART score for quality assessment of the ACI on MRI was an average of 13.7±1.8 points (11-16), with a complete fill of the defect in 80% of lesions.

CONCLUSION

Medial patellofemoral ligament reconstruction with simultaneous ACI showed good clinical results in recurrent patella dislocation with traumatic cartilage lesions grade IV. No patella re-dislocation occurred and the ACI was successful in 80% of patients according to MRI. Subjective and objective scores improved but combined surgery is inferior to reports from the literature on MPFL reconstruction alone without cartilage damage.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Dynamic versus static reconstruction of the medial patellofemoral ligament for recurrent lateral patellar dislocation

PURPOSE

To compare clinical and radiological outcomes of static and dynamic medial patellofemoral ligament (MPFL) reconstruction techniques.

METHODS

In a retrospective, matched-paired, cohort analysis, 30 patients surgically treated for recurrent lateral patellar dislocation were divided into two groups of 15 patients matched for inclusion and exclusion criteria. The static technique group underwent rigid fixation of the gracilis tendon at the anatomic femoral MPFL insertion and the superomedial border of the patella; the dynamic technique group underwent detachment of the gracilis tendon at the pes anserinus with fixation to the proximal medial patellar margin via tunnel transfer obliquely through the patella. Kujala, Lysholm, and Tegner scores; pain level; and pre- and postoperative radiographic changes of patellar height, patellar tilt, and bisect offset were compared.

RESULTS

No significant between-group differences were found in mean Kujala, Tegner, Lysholm, or visual analogue scale scores or radiographic parameters. One case of resubluxation was observed in the dynamic group. All but one patient in each group would have been willing to undergo the procedure again.

CONCLUSIONS

Both techniques provided satisfactory short-term outcomes.

LEVEL OF EVIDENCE

III.

Anatomic medial patellofemoral ligament reconstruction using patellar suture anchor fixation for recurrent patellar instability

PURPOSE

The purpose of this study was to prospectively evaluate clinical and radiographic outcomes following anatomic medial patellofemoral ligament (MPFL) reconstruction using patellar suture anchor fixation for recurrent patellar instability.

METHODS

Twenty patients (20 knees) were enrolled in this study. The median age was 21 years, and the median follow-up was 34.5 months. Reconstruction was performed using a hamstring autograft fixed with two suture anchors at native patellar site of the MPFL. No patient had undergone additional medial tibial tuberosity transfer. Clinical scores (Kujala, Lysholm, and Tegner score) and apprehension test were completed preoperatively and at the follow-up. Preoperative and follow-up radiographic assessments included modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle.

RESULTS

The preoperative Kujala and Lysholm scores were 52.6±12.4 and 49.2±10.7, and at follow-up visits, corresponding values were 90.9±4.5 (p<0.001) and 90.9±5.2 (p<0.001). Tegner score increased from 3.0 (range 1-4) to 5.0 (range 4-7) (p<0.001). The apprehension test was positive in all patients preoperatively, but only positive in one patient at follow-up. All radiographic assessments were significantly improved; modified Insall-Salvati index (from 1.75 to 1.65) (p=0.002), congruence angle (from 6.3° to -7.0°) (p<0.001), and lateral patellofemoral angle (from 2.1° to 4.9°) (p=0.008). No patient experienced a patellar fracture or redislocation.

CONCLUSION

These results are comparable to those of bone tunnel techniques reported in the literature. This study shows that anatomic MPFL reconstruction using two suture anchors is a reliable treatment option.

LEVEL OF EVIDENCE

Case series with no comparison group, Level IV.

A validated cadaveric model of trochlear dysplasia

PURPOSE

Despite the high prevalence of trochlear dysplasia among patients with patellar instability, it is not well studied and is infrequently addressed surgically. The lack of a validated cadaveric model of trochlear dysplasia may be a contributing factor. The goal of this study was to develop a simple, reproducible, and realistic cadaveric model of trochlear dysplasia by surgically modifying cadaveric femora with normal anatomy and then to validate this model through the use of mechanical and fluoroscopic measurements.

METHODS

The floor of the trochlear groove was surgically elevated using an inflatable bone tamp in eight cadaveric femora. The trochlear depth (TD) was measured with a custom-designed measuring device, and radiographic markers of dysplasia (sulcus angle, crossing sign, and prominence) were assessed before and after surgical modification.

RESULTS

The average TD was 3.6±1.4, 4.6±1.1, and 5.1±1.0 mm prior to reverse trochleoplasty (RT) and 1.0±1.8, 2.3±1.3, and 3.3±2.5 mm following RT at 0°, 20°, and 40° of flexion, respectively. These direct measurements of TD were confirmed with fluoroscopy. The sulcus angle averaged 141° prior to RT and 157° after RT. The average prominence across all specimens was 3.3±0.7 mm before RT, and 5.5±1.5 mm after RT. Finally, the crossing sign was found to be absent in all knees prior to RT and present in 7 of the 8 after RT.

CONCLUSIONS

The results of this study show that elevation of the trochlear floor with an inflatable bone tamp can reproducibly create a simulated dysplastic trochlea. This model may be useful in biomechanical studies of treatments for patellofemoral instability.

Variations in kinematics and function following patellar stabilization including tibial tuberosity realignment

PURPOSE

The current study was performed to characterize the influence of patellar stabilization procedures on patellofemoral and tibiofemoral dynamic motion.

METHODS

Six knees were evaluated pre-operatively and 1 year or longer following stabilization via tibial tuberosity realignment, with simultaneous medial patellofemoral ligament reconstruction performed for five knees. Knees were imaged during extension against gravity using a dynamic CT scanner. Models representing each knee at several positions of extension were reconstructed from the images. Local coordinate systems were created within one femur, patella and tibia for each knee, with shape matching of the bones used to transfer the coordinate axes to the other models. The patellar lateral shift and tilt and tibial external rotation were quantified based on the reference axes and interpolated to flexion angles from 5° to 40°. Pre-operative and post-operative data were compared with the paired t tests.

RESULTS

Surgical realignment significantly decreased the average patellar lateral shift and tilt at low flexion angles. At 5°, surgical realignment decreased the average lateral shift from 15.5 (6.3) to 8.5 (4.7) mm and decreased the average lateral tilt from 20.8 (9.4)° to 13.8 (6.4)°. The changes were statistically significant (p<0.05) at 5° and 10° of flexion, as well as 20° for lateral shift. The average tibial external rotation also increased significantly at 30° and 40° following surgery.

CONCLUSION

Patellar stabilization including a component of tuberosity realignment reduces patellar lateral shift and tilt at low flexion angles, but the long-term influence of increased tibial external rotation on tibiofemoral function is currently unknown.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Medial retinacular flap advancement and arthroscopic lateral release for symptomatic chronic patellar lateral subluxation with tilting

PURPOSE

The purpose of this study was to investigate outcomes of surgical treatment in patients with symptomatic chronic patellar lateral subluxation with tilting.

METHODS

Thirty-two patients (38 knees) underwent arthroscopic lateral release and mini-open advancement of medial retinacular flap for the treatment of symptomatic chronic patellar lateral subluxation with tilting with a mean follow-up of 52.0±11.4 months. The mean age at surgery was 24.7±8.8 years, and the duration of symptoms was 4.8±4.1 years. The patellofemoral function of the knee was evaluated before surgery and at the clinical follow-up using the Kujala functional score.

RESULTS

Thirty-six knees (95%) showed excellent or good results after surgery. Two knees with grade IV chondromalacia of the patella had fair results with persistent apprehension signs and persistent pain. The Kujala patellofemoral functional scores improved by an average of 20.9 points from a mean value of 71.8±12.1 preoperatively to 92.7±10.7 postoperatively (P<0.01). Radiographically, there were significant improvements in congruence angle from 23.4°±7.9° preoperatively to -7.2°±6.4° postoperatively (P<0.01) and in the lateral patellofemoral angle from -8.6°±6.8° preoperatively to 6.3°±4.2° postoperatively (P<0.01).

CONCLUSIONS

Medial retinacular flap advancement and arthroscopic lateral release offer a promising treatment for symptomatic chronic patellar lateral subluxation and tilt without frank traumatic episode.

LEVEL OF EVIDENCE

Retrospective study, Level IV.

Medial Patellofemoral Ligament Reconstruction for Patellar Dislocation: A Systematic Review

Background:

With improved understanding of the biomechanical importance of the medial patellofemoral ligament (MPFL), its reconstruction for patellar dislocation has become increasingly popular. The aim of this systematic review was to critically determine the effectiveness of MPFL reconstruction for patellar dislocation.

Hypothesis:

MPFL reconstruction for patellar dislocation leads to a low redislocation rate with improved Kujala scores.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A literature search was performed using Embase and Medline (Ovid) databases. Inclusion criteria included first-time and recurrent patellar dislocation, subluxation, or persistent instability with a minimum follow-up of 12 months and documentation of postoperative redislocation rate or Kujala score. The studies were systematically appraised, and a meta-analysis was performed.

Results:

Twenty-two studies were included: 2 randomized controlled trials, 3 parallel case series, and 17 case series. There were a total of 655 knees in the review, with an age range at time of surgery from 11 to 52 years. The pooled postoperative redislocation rate from all 17 case series showed a mean of 2.44%. The pooled preoperative Kujala scores from 12 case series showed a mean of 51.6 (95% CI, 46.71-56.49). The pooled postoperative Kujala scores from 16 case series showed a mean of 87.77 (95% CI, 85.15-90.39).

Conclusion:

Although the studies were of low quality, the meta-analysis of 17 case series shows that MPFL reconstruction for recurrent patellar dislocation results in a significant improvement in Kujala scores, a low redislocation rate, and acceptable complication rate. Randomized trials would be needed to draw influences on the superiority of MPFL reconstruction compared with other treatments.

Return to activity after medial patellofemoral ligament repair or reconstruction

PURPOSE

This study aimed to determine the ability of patients to return to activity after medial patellofemoral ligament (MPFL) reconstruction or repair for patellar instability.

METHODS

A systematic review was performed using multiple databases. Studies reporting outcomes with Tegner scores after repair or reconstruction of the MPFL were included. Surgical technique, Tegner scores, and episodes of recurrent patellar instability were recorded.

RESULTS

Ten articles with a total of 402 patients were included. The mean preoperative Tegner score was 4.7 (2.9 to 7.5). The mean postoperative Tegner score was 5.8 (4.0 to 7.7). Forty-nine patients (12.2%) had a recurrent episode of instability, 11 of whom required additional corrective procedures. There was a statistically significant larger failure rate among those who underwent MPFL repair (26.9%) than those who underwent reconstruction (6.6%) or medial retinacular repair/plication (16.5%).

CONCLUSIONS

Recurrent dislocation was higher in patients who underwent MPFL repair rather than reconstruction. However, repair and reconstruction had similar Tegner scores. Repair or reconstruction of the soft tissue structures contributing to patellofemoral instability is successful in returning patients to preinjury activity levels.

LEVEL OF EVIDENCE

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

Reconstruction of the Medial Patellofemoral Ligament: Clinical Outcomes and Return to Sports

BACKGROUND

Recent studies have shown that medial patellofemoral ligament (MPFL) reconstruction using a standardized technique provides significant improvements in all outcome scoring systems, with low complication rates and good patient satisfaction. Although numerous studies have assessed clinical results, there is little published literature investigating return to sporting activities after reconstruction of the MPFL.

PURPOSE

To demonstrate postoperative outcomes and the return-to-sports rate a minimum of 2 years after isolated MPFL reconstruction in a young patient cohort.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 2007 and 2010, a total of 72 isolated MPFL reconstructions (in 68 patients) were performed for recurrent patellar dislocation. Pre- and postoperative knee assessment included a thorough history of symptoms and a clinical examination consisting of crepitus, range of motion, patellofemoral pain, and patellar apprehension. Knee function was assessed using the Kujala score, International Knee Documentation Committee score, Tegner activity score, visual analog scale (VAS), and Activity Rating Scale (ARS).

RESULTS

Of patients who participated in sports preoperatively (62/68 patients), 100% returned to sports after MPFL reconstruction; 53% returned at equal or higher levels, whereas 47% returned at lower levels. Fifty-four of 68 patients (79.4%) rated themselves as very satisfied or satisfied with the results. The median Kujala score improved significantly from 66 to 87.5 and the median International Knee Documentation Committee score from 60 to 79.8. The median VAS for pain score illustrated significant preoperative to postoperative improvement, from 4 to 2. Conversely, patients' activity levels according to the Tegner activity score dropped from 4.5 to 4, and the median Activity Rating Scale score dropped from 6 to 3. There was also a persistent instability rate of 10% as well as a slight loss of knee flexion in 24 of 72 knees.

CONCLUSION

Reconstruction of the MPFL is a safe and effective treatment for patellofemoral instability without severe trochlear dysplasia and allows most patients to engage in regular sports activities 2 years postoperatively, at least at a recreational level. However, potential complications, such as persistent instability, pain, and loss of flexion, must be considered.

Trochleoplasty versus nontrochleoplasty procedures in treating patellar instability caused by severe trochlear dysplasia

PURPOSE

The purpose of this study was to compare the clinical outcomes and postoperative complication rates between patients who underwent trochleoplasty or nontrochleoplasty procedures in treating patellar instability caused by severe trochlear dysplasia (STD).

METHODS

The PubMed database was searched using specific inclusion and exclusion criteria for clinical studies reporting indexed orthopaedic treatments of patellar instability caused by STD (Dejour type B to D). Participants within studies were classified into one of the 2 treatment groups: (1) the trochleoplasty group (group T) and (2) the nontrochleoplasty group (group N). Clinical outcomes and postoperative complications were analyzed.

RESULTS

Seventeen studies were finally included. There were in total 459 knees that underwent the indexed orthopaedic treatments of patellar instability caused by STD (Dejour type B to D). Eleven studies, including 329 knees, formed the trochleoplasty group (group T), and the remaining 6 studies, including 130 knees, composed the nontrochleoplasty group (group N). All the clinical outcomes within groups had improved significantly (P < .05) at the final follow-up. No studies directly compared the clinical outcomes between the 2 groups. The postoperative complication analysis showed superior results for the trochleoplasty group in (1) patellar redislocation rate and (2) percentage of patellofemoral osteoarthritis (Iwano grade 2 or greater) progression findings but an inferior outcome with respect to the range of motion (ROM) deficit compared with the nontrochleoplasty group.

CONCLUSIONS

This systematic review showed significant postoperative improvements both in patients undergoing the trochleoplasty procedures and in patients undergoing the nontrochleoplasty procedures for the treatment of patellar instability caused by STD in all the included studies. However, there is limited evidence regarding the comparative advantages toward the optimal treatment. The postoperative complication rate has been considered to be the best measurement of operative success. To prevent the patella from redislocating and patellofemoral osteoarthritis from progressing, trochleoplasty procedures should be considered. Meanwhile, one should be cautious about the postoperative ROM deficit before choosing trochleoplasty procedures.

LEVEL OF EVIDENCE

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

Clinical and Functional Outcomes following Primary Repair versus Reconstruction of the Medial Patellofemoral Ligament for Recurrent Patellar Instability

Background. The purpose of this study was to compare outcomes of medial patellofemoral ligament (MPFL) repair or reconstruction. Methods. Fourteen knees that underwent MPFL repair and nine (F5, M4) knees that underwent reconstruction at our institution were evaluated for objective and subjective outcomes. The mean age at operation was 20.1 years for repair and 19.8 years for reconstruction. All patients had a minimum of 2 years of follow-up (range: 24-75 months). Patient subjective outcomes were obtained using the International Knee Documentation Committee (IKDC) and Kujala patellofemoral subjective evaluations, as well as Visual Analog (VAS) and Tegner Activity Scales. Bilateral isometric quadriceps strength and vastus medialis obliquus (VMO) and vastus lateralis (VL) surface EMG were measured during maximal isometric quadriceps contractions at 30° and 60° of flexion. Results. There were no redislocations in either group. There was no difference in IKDC (P = 0.16), Kujala (P = 0.43), Tegner (P = 0.12), or VAS (P = 0.05) scores at follow-up. There were no differences between repair and reconstruction in torque generation of the involved side at 30° (P = 0.96) and 60° (P = 0.99). In addition, there was no side to side difference in torque generation or surface EMG activation of VL or VMO. Conclusions. There were minimal differences found between patients undergoing MPFL repair and MPFL reconstruction for the objective and subjective evaluations in this study.

Medial patellofemoral ligament reconstruction with a looped semitendinosus tendon, using knotless anchor fixation on the patella and hybrid fixation on the femur

Medial patellofemoral ligament (MPFL) reconstruction is a reliable surgical method for stabilizing a dislocating patella, with multiple techniques previously described. Although outcomes are generally favorable, the procedure is technically demanding and relies on precise identification of native MPFL insertion sites, secure fixation of the graft to these sites, and appropriate graft tension. We describe a technique for MPFL reconstruction with a looped semitendinosus tendon. The 2 free limbs of the graft are secured into blind-end patellar sockets with knotless anchors, and the looped end is initially secured into a medial femoral socket with a button on the opposite (lateral) cortex. Use of an adjustable-loop button allows for gradual adjustment of graft tension, as well as re-tensioning after cycling of the knee, before final aperture fixation on the femur with an interference screw.

Does degree of trochlear dysplasia and position of femoral tunnel influence outcome after medial patellofemoral ligament reconstruction?

BACKGROUND

The medial patellofemoral ligament (MPFL) is the main restraining force against lateral patellar displacement. It is disrupted after patellar subluxation or dislocation. Reconstruction of the MPFL is frequently performed when nonoperative management fails and the patient experiences recurrent patellar dislocation.

PURPOSE

To determine the relationship between the degree of trochlear dysplasia and femoral tunnel position and outcome after MPFL reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 68 patients (72 knees) with recurrent dislocation of the patella underwent MPFL reconstruction. The mean follow-up was 31.3 months (range, 13-72 months). Clinical and functional outcomes were recorded using the Kujala, Lysholm, and Tegner scores. Postoperative complications, participation in sporting activity, and overall patient satisfaction were determined. Radiographs were analyzed to evaluate congruence angle, lateral patellofemoral angle, patellar height, trochlear dysplasia, trochlear boss height, and position of the femoral tunnel.

RESULTS

The mean Kujala, Lysholm, and Tegner scores postoperatively were 76.2, 73.8, and 3.6, respectively (n = 61). The mean congruence angle (n = 30) improved from 22.5° to 1.0° postoperatively (P = .000038), the lateral patellofemoral angle (n = 30) improved from 7.4° to 7.8° postoperatively (P = .048), and the patellar height (n = 46) using the Caton-Deschamps method improved from 1.1 to 1.0 postoperatively (P = .000016). Mild trochlear dysplasia grade A/B was found in 89% of patients (n = 54), and 11% of patients (n = 7) had severe grade C/D dysplasia. The mean distance from the anatomic insertion of the MPFL to the center of the tunnel was 9.3 mm (range, 0.5-28.2 mm), with 71.7% thought to be within 10 mm of the anatomic position defined by Schottle (n = 46). When patients with high-grade trochlear dysplasia were excluded, anatomically placed femoral tunnels demonstrated significantly better clinical scores than did tunnels not placed anatomically (Kujala score, P = .028; Lysholm score, P = .012). A multivariate logistic regression analysis also demonstrated that the distance of the femoral tunnel from the anatomic position predicted clinical outcome (Kujala score, P = .043; Lysholm score, P = .028). All of the patients with severe trochlear dysplasia (n = 7) suffered from recurrent dislocations postoperatively, compared with only 9.3% of patients (n = 5) with mild trochlear dysplasia (P = .0001). Four patients had patellar fractures postoperatively. Of patients with mild dysplasia, 83% were either very satisfied or satisfied with the outcome of their surgery compared with only 57% with severe dysplasia (P = .05). Of patients with mild trochlear dysplasia, 56% returned to sport postoperatively compared with only 43% of patients with severe trochlear dysplasia (P = .526).

CONCLUSION

This study demonstrates the importance of restoration of the anatomic insertion point of the MPFL when performing MPFL reconstruction and proposes that this procedure should not be performed in isolation in patients with high-grade trochlear dysplasia.

Guidelines for medial patellofemoral ligament reconstruction in chronic lateral patellar instability

The standard surgical approach for chronic lateral patellar instability with at least two documented patellar dislocations is to stabilize the patella by using an anatomic medial patellofemoral ligament reconstruction with a mini-open technique and a graft that is stronger than the native ligament to compensate for the uncorrected predisposing factors underlying patellar instability. Even though medial patellofemoral ligament reconstruction has evolved notably during the past two decades, many aspects of the surgical technique need to be refined, and more information is needed toward this end. Adequate positioning of the graft on the femur, as well as inducing the appropriate degree of tension, are critical steps for the overall outcome of medial patellofemoral ligament reconstruction. Moreover, it is necessary in some cases to pair medial patellofemoral ligament reconstruction with other surgical procedures to address additional patellar instability risk factors, such as trochlear dysplasia, malalignment, and patella alta.

The effect of femoral tunnel position and graft tension on patellar contact mechanics and kinematics after medial patellofemoral ligament reconstruction

BACKGROUND

An incorrect femoral tunnel position or inappropriate graft tensioning during medial patellofemoral ligament (MPFL) reconstruction may cause altered patellofemoral joint kinematics and contact mechanics, potentially resulting in pain and joint degeneration.

HYPOTHESIS

Nonanatomic positioning of the tunnel or graft overtensioning during MPFL reconstruction will have an adverse effect on patellar tracking and patellofemoral joint contact mechanics.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric knees were placed on a customized testing rig, with the femur fixed and the tibia mobile through 90° of flexion. Individual heads of the quadriceps muscle and the iliotibial band were separated and loaded with 205 N in anatomic directions using a system of cables and weights. Patellofemoral contact pressures and patellar tracking were measured through the flexion range at 10° intervals using Tekscan pressure-sensitive film inserted between the patella and trochlea and an optical tracking system. The MPFL was transected and then reconstructed using a double-strand gracilis tendon graft. Pressures and kinematics were recorded for reconstructions with the graft positioned in anatomic, proximal, and distal tunnel positions. Measurements were then repeated with an anatomic tunnel and graft tension of 2 N, 10 N, and 30 N, fixed at 3 different flexion angles of 0°, 30°, and 60°. Statistical analysis was undertaken using repeated-measures analysis of variance, Bonferroni post hoc analysis, and paired t tests.

RESULTS

For a graft tensioned to 2 N, anatomically positioned MPFL reconstruction restored intact medial and lateral joint contact pressures and patellar tracking (P > .05), but femoral tunnels positioned proximal or distal to the anatomic origin resulted in significant increases in peak and mean medial pressures and medial patellar tilt during knee flexion or extension, respectively (P < .05). Grafts tensioned with 10 N or 30 N also caused significant increases in medial pressure and tilt. Graft fixation at 30° or 60° restored all measures to intact values (P > .05), but fixation at 0° caused significant increases (P < .05) in medial joint contact pressures compared with intact knees.

CONCLUSION

Anatomically positioned reconstruction with 2-N tension fixed at 30° or 60° of knee flexion restored joint contact pressures and tracking. However, graft overtensioning or femoral tunnels positioned too proximal or distal caused significantly elevated medial joint contact pressures and increased medial patellar tilting. The importance of a correct femoral tunnel position and graft tensioning in restoring normal patellofemoral joint kinematics and articular cartilage contact stresses is therefore evident.

CLINICAL RELEVANCE

A malpositioned femoral tunnel or overtensioned graft during MPFL reconstruction resulted in increased medial contact pressures and patellar tilting. This may lead to adverse outcomes such as early degenerative joint changes or pain if occurring in a clinical population.

Medial patellofemoral ligament reconstruction in patellar instability

BACKGROUND

Medial patellofemoral ligament (MPFL) is one of the major static medial stabilising structures of the patella. MPFL is most often damaged in patients with patellar instability. Reconstruction of MPFL is becoming a common surgical procedure in treating patellar instability. We hypothesised that MPFL reconstruction was adequate to treat patients with patellar instability if the tibial tubercle and the centre of the trochlear groove (TT-TG) value was less than 20 mm and without a dysplastic trochlea.

MATERIALS AND METHODS

30 patients matching our inclusion criteria and operated between April 2009 and May 2011 were included in the study. MPFL reconstruction was performed using gracilis tendon fixed with endobutton on the patellar side and bio absorbable interference screw or staple on the femoral side. Patients were followed up with subjective criteria, Kujala score and Lysholm score.

RESULTS

The mean duration of followup was 25 months (range 14-38 months). The mean preoperative Kujala score was 47.5 and Lysholm score was 44.7. The mean postoperative Kujala score was 87 and Lysholm score was 88.06. None of the patients had redislocation.

CONCLUSION

MPFL reconstruction using gracilis tendon gives excellent results in patients with patellar instability with no redislocations. Some patients may have persistence of apprehension.

Does knee joint proprioception alter following medial patellofemoral ligament reconstruction?

BACKGROUND

This study firstly aimed to determine whether proprioception deficits, as measured by joint position sense (JPS), occur in people following recurrent patellar dislocations. Secondly, to determine whether JPS changes following medial patellofemoral ligament reconstruction (MPFL) reconstruction for patellar instability.

METHODS

Thirty people following recurrent patellar dislocation were recruited. Pre-operative JPS was assessed using the passive angle reproduction test. Through this, an assessor moved a participant's limb to a target position. This was returned to neutral, before finally moving the limb again, whilst requiring the participant to indicate when they thought the target angle was reached. The actual angular error (AAE) was calculated as the difference between the perceived angle and target angle. Clinical outcomes included the Kujala Patellofemoral Disorder Score, the International Knee Documentation Committee (IKDC) form, pain, knee motion, extensor muscle strength and frequency of patellar dislocation. Outcomes were assessed pre-operative, 6 weeks, 3 and 12 months.

RESULTS

Mean AAE was 2.2° (inner range) to 3.9° (mid-range); this was not clinically significant. There was no statistically significant difference between the baseline-and-6 week, 6 week-and-3 month or baseline-and-12 month AAE measures (p=0.38 to 1.00). There was a statistically significant improvement in functional outcomes as measured by the Kujala score, IKDC form, reduced pain and increased extension strength from baseline to 12 months (p<0.01).

CONCLUSIONS

Following recurrent patellar dislocation, patients exhibit minimal deficits in JPS. Whilst MPFL reconstruction significantly improved clinical and functional outcomes for this population, this operation did not significantly alter JPS during the first post-operative year.

Medial reefing without lateral release for recurrent patellar instability: midterm and long-term outcomes

BACKGROUND

There is no consensus on the optimal surgical technique for recurrent patellofemoral instability. Despite many different surgical procedures discussed in the literature, there are few studies with long-term outcomes.

HYPOTHESIS/PURPOSE

The purpose of this study was to compare subjective and objective preoperative data from patients with recurrent patellar instability and normal alignment to midterm and long-term outcomes after an arthroscopically assisted medial reefing technique. The hypothesis was that the previously reported successful outcomes at 60 months would be well maintained over time.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 19 patients (20 knees) with recurrent patellar instability and normal bony anatomy underwent arthroscopically assisted medial reefing without lateral release. They were evaluated preoperatively and then at midterm (average, 63 months) and long-term (average, 142 months) follow-ups. Patients underwent a history assessment, physical examination, and radiographic evaluation. Outcomes evaluated included Lysholm and Tegner scores, subjective data, and examination and radiographic findings. Operative reports were reviewed for the presence of chondral lesions. Comparative statistics were utilized (P < .05).

RESULTS

All patients were satisfied with their surgery results and would undergo the procedure again. There was 1 recurrent subluxation and no recurrent dislocations. Subjective symptom scores demonstrated significant improvement from preoperative to midterm and long-term follow-ups for pain, instability, and swelling. Both Lysholm and Tegner scores improved significantly from preoperative to midterm and long-term follow-ups. At long-term follow-up, 70% of the patients reported excellent or good results, 5 patients reported fair results, and 1 patient reported a poor result. However, Tegner activity scores decreased significantly from midterm to long-term follow-ups. Significant improvement from preoperative to midterm and long-term follow-ups was demonstrated in physical examination findings including decreases in patellar apprehension and patellar quadrant glide; however, there was no significant difference in retropatellar pain or range of motion. For radiographic measurements, the lateral patellofemoral angle was significantly improved from preoperative to midterm and long-term follow-ups. At long-term radiographic analysis, 5 knees (25%) had narrowing of the patellofemoral joint space, 10 knees (50%) revealed patellofemoral osteophytes, and 7 knees (35%) demonstrated a medial ossicle. The presence of preoperative chondral lesions resulted in significantly lower Lysholm and Tegner scores and increased findings of osteoarthritis at long-term follow-up.

CONCLUSION

Arthroscopically assisted medial reefing, without lateral release, is an effective long-term treatment for patients with recurrent patellar instability and normal bony anatomy.