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

Use of contact pressure-sensitive surfaces as an indicator of graft tension in medial patellofemoral ligament reconstruction

BACKGROUND

No previous description has been made about an objective method to test the graft resistance in MPFL reconstruction intraoperatively. In our study, we aimed to obtain intraoperative objective data about the graft resistance using contact pressure-sensitive surfaces and measuring pressure formed under the graft.

MATERIALS AND METHODS

In 2012, double-layered contact pressure-sensitive Fuji Prescale Film bands were placed under MPFL in 15 fresh-frozen high above-knee amputates (Group 1) and under graft in 10 patients who underwent MPFL reconstruction (Group 2). Measured values at different flexion angles were compared between and in groups.

RESULTS

Statistical analysis was performed by Student's t test. It has been found that the pressure under the graft was higher in patients having reconstruction as compared to the pressure under natural MPFL. Decreasing pressure values were observed with increasing flexion angles in both groups.

CONCLUSION

Contact pressure-sensitive surfaces provided objective data when placed under the graft in natural MPFL and during surgery. Therefore, they may be used as an objective marker providing information about graft resistance.

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

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

An isolated medial patellofemoral ligament reconstruction with patellar tendon autograft

The aim of the study was to evaluate the results of the medial patellofemoral ligament reconstruction with a medial strip of patellar tendon autograft after a minimum 2-year followup. Ten patients (10 knees) were operated on by one surgeon, according to the modified technique, described by Camanho, without any bone plug at free graft end. The mean age of the patients was 27.2 years (ranging from 18 to 42 years). The mean follow-up period was 3 years and 7 months. All patients were reviewed prospectively. At the last follow-up visit, all the patients demonstrated a significant improvement in terms of patellofemoral joint stability, all aspects of the KOOS questionnaire, and Kujala et al.'s score (59.7 points preoperatively and 84.4 points at the last followup). No patient revealed recurrent dislocation. The SF-36 score revealed a significant improvement in bodily pain, general health, physical role functioning, social role functioning, and physical functioning domains. The described MPFL reconstruction with the use of the medial 1/3rd of patella tendon is an effective procedure that gives satisfactorily patellofemoral joint functions, improves the quality of life, and provides much pain relief. It is relatively simple, surgically not extensive, and economically cost-effective procedure.

Double-bundle medial patellofemoral ligament reconstruction with hamstring tendon autograft and mediolateral patellar tunnel fixation: a meta-analysis of outcomes and complications

Medial patellofemoral ligament (MPFL) reconstruction is used to treat patellar instability and recurrent patellar dislocation. Anatomical studies have found the MPFL to be a double-bundle structure. We carried out a meta-analysis of studies reporting outcomes of patellofemoral reconstruction using hamstring tendon autograft in a double-bundle configuration and patellar fixation via mediolateral patellar tunnels. A literature search was undertaken with no language restriction in various databases from their year of inception to July 2012. The primary outcome examined was the post-operative Kujala score. We identified 320 MPFL reconstructions in nine relevant articles. The combined mean post-operative Kujala score was 92.02 (standard error (se) 1.4, p = 0.001) using a fixed effects model and 89.45 (se 37.9, p = 0.02) using random effect modelling. The reported rate of complications with MPFL reconstruction was 12.5% (40 of 320) with stiffness of the knee being the most common. High-quality evidence in assessing double-bundle MPFL reconstruction is lacking. The current literature consists of a mixture of prospective and retrospective case series. High-quality randomised trials evaluating this procedure are still awaited.

Isolated and combined medial patellofemoral ligament reconstruction in revision surgery for patellofemoral instability: a prospective study

BACKGROUND

Persistent pain and redislocations after surgical treatment of patellofemoral instability are described in up to 40% of patients. However, prospective outcome data about revision surgery are missing.

PURPOSE

To evaluate the clinical outcome after revision medial patellofemoral ligament (MPFL) reconstruction using isolated and combined procedures, with a follow-up of 24 months.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Study participants were 42 patients (median age, 22 years; range, 13-46 years) who underwent revision surgery between January 2007 and December 2009 because of persistent patellofemoral instability after a mean of 1.8 previous failed surgical interventions (lateral release, medial imbrication/vastus medialis obliquus distalization, medialization of the tuberosity). An isolated MPFL reconstruction was performed in 15 cases, while a combination procedure was performed in 27 cases. The clinical results were evaluated preoperatively and 24 months postoperatively using the International Knee Documentation Committee (IKDC), Kujala, and Tegner scores as well as a subjective questionnaire. Patellar shift, tilt, and height, as well as level of degeneration, were defined preoperatively and at the latest follow-up on plain radiographs and magnetic resonance imaging.

RESULTS

At 24-month follow-up, 87% of the patients were satisfied or very satisfied with the treatment. No apprehension or redislocation was reported at follow-up, and there was a significant decrease in pain during daily activities. There were significant improvements (P < .001) in IKDC (from 50 to 80), Kujala (from 51 to 85), and Tegner scores (from 2.4 to 4.9). Patellar shift, tilt, and height decreased significantly (P < .05) to anatomic values, and there was no aggravation to the level of pre-existing degeneration. No significant difference was noticed between the isolated and combined procedures.

CONCLUSION

As patellofemoral instability is a multifactorial problem, revision surgery should be indicated only after a comprehensive examination. The results of this study show that MPFL reconstruction, alone or in combination, seems to be an effective treatment for recurrent patellar dislocations after a failed previous surgery, leading to significant increases in stability and functionality as well as a reduction in pain.

The contemporary management of anterior knee pain and patellofemoral instability

In this review the evidence for the management of patients with patellofemoral disorders is presented confined to anterior knee pain and patellar dislocation (excluding patellofemoral arthritis). Patients present along a spectrum of these two problems and are best managed with both problems considered. The key to managing these patients is by improving muscle function, the patient losing weight (if overweight), and judicious use of analgesics if pain is an important feature. Hypermobility syndrome should always be looked for since this is a prognostic indicator for a poor operative outcome. Operations should be reserved for those with correctable anatomical abnormalities that have failed conservative therapy. The current dominant operation is a medial patellofemoral ligament reconstruction.

Treating patella instability in skeletally immature patients

PURPOSE

The purpose of this study was to comprehensively and systematically review the current evidence for orthopaedic treatment of immature and adolescent patients with acute and chronic patellar instability.

METHODS

We searched the online databases PubMed, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews for relevant publications on patellar instability. All dates and languages were included.

RESULTS

Twenty articles reporting on a total of 456 knees in 425 patients (131 male patients, 294 female patients) followed-up for 56.7 ± 42.2 months on average were included in the analysis. Two studies focused specifically on conservative versus surgical treatment in acute dislocations and reported no difference in outcomes after 7 and 14 years, even in the face of slight trochlear dysplasia. For recurrent instability, we found consistent beneficial effects from surgical stabilization on clinical scores, postoperative stability, and radiographic assessment. There is no evidence for growth disturbance with surgical patellar stabilization in immature patients.

CONCLUSIONS

The current best evidence does not support the superiority of surgical intervention over conservative treatment in an acute patellar dislocation. However, anatomic variations and their effect on healing should be considered and included in decision making. In recurrent patellar instability in pediatric and adolescent patients with normal or restored knee anatomy, reconstruction of the medial patellofemoral ligament (MPFL) is the most effective treatment option and can be done safely, together with extensor realignment as needed.

LEVEL OF EVIDENCE

Level IV, systematic review of mixed-level studies.

Surgical treatment of a chronically fixed lateral patella dislocation in an adolescent patient

Acute patellar dislocation or subluxation is a common cause for knee injuries in the United States and accounts for 2% to 3% of all injuries. Up to 49% of patients will have recurrent subluxations or dislocations. Importance of both soft tissue (predominantly, the medial patellofemoral ligament, MPFL, which is responsible for 60% of the resistance to lateral dislocation) and bony constraint of femoral trochlea in preventing subluxation and dislocation is well documented. Acute patella dislocation will require closed reduction and management typically consist of conservative or surgical treatment depending on the symptoms and recurrence of instability. Most patients are diagnosed and treated in a timely manner. We present a 15 years old male with a missed traumatic lateral patella dislocation during childhood. The patient presented as an adolescent with a chronically fixed lateral patella dislocation and was management with surgery. The key steps in the surgical reconstruction of this patient required first mobilizing the patella with a lateral retinacular release and V-Y lengthening of the shortened or contracted quadriceps tendon. Then a combination of MPFL reconstruction using the semitendinosis autograft, tibial tubercle osteotomy with anterio-medialization, and lateral facetectomy was performed. At the one-year follow-up, our patient had improved knee range of motion and decrease in pain. Chronically fixed lateral dislocated patella is a rare and complex problem to manage in older patients that will require a thorough work-up and appropriate surgical planning along with reconstruction.

Short-/intermediate-term outcomes after medial patellofemoral ligament reconstruction in the treatment of chronic lateral patellofemoral instability

PURPOSE

Disruption of the medial patellofemoral ligament (MPFL) is now considered the essential lesion of recurrent lateral patellar dislocation in patients with normal lower extremity alignment. Reconstruction of the MPFL is a technique gaining significant success in the treatment of patients with this disabling condition.

HYPOTHESIS

Reconstruction of the MPFL in patients with chronic patellar instability and normal lower extremity alignment will improve knee function and symptoms, with a high percentage of patients achieving good to excellent results at early follow-up.

STUDY DESIGN

Case series; Level of evidence; 4.

METHODS

A consecutive series of patients with lateral patellofemoral instability who underwent MPFL reconstruction were reviewed. Reconstruction was performed with either soft tissue allograft (23 patients) or hamstring tendon autograft (12 patients). Outcomes were determined by patient scores from the Kujala Anterior Knee Pain Scale, recurrence of patellar instability, and patient function at a minimum of 12 months of postoperative follow-up.

RESULTS

Thirty-five patients were followed for a mean of 21.0 months (range, 12-45 months) after surgery. The Kujala subjective knee score improved significantly from 49.0 preoperatively to 89.5 postoperatively (P < 0.001). No statistical significance was found between postoperative Kujala scores and graft type, or time from initial injury to surgical reconstruction. A firm endpoint to lateral translation of the patella, and no feelings of apprehension were noted in all patients at most recent follow-up. The majority of patients noted that they were more active than before reconstructive surgery, with 86% participating in "strenuous" to "very strenuous" activities at the time of follow-up. No recurrent dislocations were reported.

CONCLUSION

Reconstruction of the MPFL provides excellent stability and functional outcomes for patients with recurrent patellar instability.

Medial patellofemoral ligament reconstruction: the superficial quad technique

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a routine procedure for patellar instability. The majority of the techniques require hardware fixation or a bony procedure at the patella. However, most of the complications described in the literature can be attributed to patellar fixation. The "superficial quad technique" uses the superficial slip of the quadriceps tendon as the graft material, which provides a better anatomic match to the native MPFL.

HYPOTHESIS

The superficial quad technique provides anatomic patellar fixation without a bony procedure and without patellar complications.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The study included 32 patients (10 male, 22 female; mean age, 25 years) who underwent MPFL reconstruction using the superficial quad technique and who were followed for a mean duration of 38 months. Objective assessment was performed and Kujala scores were obtained preoperatively and at the time of final follow-up.

RESULTS

There were no patellar complications, including redislocation, in the present study. The mean Kujala score improved to 91.25 (range, 73-100) from a preoperative score of 49.31 (range, 23-62).

CONCLUSION

The results were comparable with those of other studies in the literature that used hamstring grafts, but without associated patellar complications. The superficial quad technique uses graft material that is a better anatomic match to the native MPFL. It provides anatomic patellar fixation without a bony procedure.

Complications of medial patellofemoral ligament reconstruction in young patients

BACKGROUND

The medial patellofemoral ligament (MPFL) has been recognized as the primary restraint to lateral subluxation of the patella. Reconstruction of the MPFL for patellar instability has demonstrated early clinical success, but postoperative complications have rarely been reported, especially in young patients.

PURPOSE

To assess early complications (<3 years) of MPFL reconstruction in young patients.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The charts and radiographs of all patients who underwent MPFL reconstruction between 2005 and 2011 were retrospectively reviewed to identify postoperative complications. A complication was considered major if the patient required hospitalization or further surgery. Each complication was analyzed to identify the technical factors related to it.

RESULTS

A total of 179 knees underwent MPFL reconstruction during the study period. There were 38 complications in 29 knees (16.2%), with 34 major and 4 minor. Major complications included recurrent lateral patellar instability (8 patients), knee motion stiffness with flexion deficits (8 patients), patellar fractures (6 patients), and patellofemoral arthrosis/pain (5 patients). Eighteen of 38 (47%) complications were secondary to technical factors and were considered preventable. Female sex and bilateral MPFL reconstructions were risk factors associated with postoperative complications.

CONCLUSION

Complications occurred in 16.2% of MPFL reconstruction surgeries for patellar instability in young patients, with almost half resulting from technical problems. Patients should be counseled preoperatively on the risk of potential complications.

Double-bundle anatomical versus single-bundle isometric medial patellofemoral ligament reconstruction for patellar dislocation

PURPOSE

The purpose of this study was to evaluate reconstruction of the medial patellofemoral ligament (MPFL) using the double-bundle anatomical or single-bundle isometric procedure with respect to the patients' clinical outcomes.

METHODS

In this retrospective study, we evaluated the clinical outcome of double-bundle anatomical versus single-bundle isometric reconstruction of the MPFL for patellar dislocation patients. Sixty-three patients were included in this study from August 2004 to January 2008. From August 2004 to September 2006, MPFL reconstruction using a single-bundle isometric technique was performed in 21 patients (26 knees). Since October 2006, the double-bundle anatomical reconstruction of the MPFL has been used as the routine surgical procedure. It was performed in 37 patients (44 knees). Fifty-eight patients (70 knees) could be followed up. According to the different techniques, we divided the patients into two groups: group D with double-bundle anatomical reconstruction (37 patients) and group S with single-bundle isometric reconstruction (21 patients). Clinical evaluation consisted of the number with a patellar re-dislocation, patellar apprehension sign, Kujala score, subjective questionnaire score, the patella lateral shift rate and patellar tilt angle measured by cross-sectional CT scan.

RESULTS

According to the Kujala score and the subjective questionnaire score, the outcome of the double-bundle group was better than the outcome of the single-bundle group especially in the long-term. Patellar re-dislocation occurred in three patients in the group S, while no re-dislocation occurred in the group D. In total, 26.9 % of group S was considered to have patellar instability, compared to 4.54 % of the group D. After operation, the patellar tilt angle (PTA) and the patella lateral shift rate (PLSR) were restored to the normal range, with statistical significance (P < 0.05) compared to the preoperative state.

CONCLUSION

Single- and double-bundle reconstruction of the MPFL can both effectively restore patella stability and improve knee function. However, outcomes in the follow-up period showed that the double-bundle surgery procedure was much better than in single-bundle surgery.

Patella instability: building bridges across the ocean a historic review

The diagnosis of and treatment for musculoskeletal disease and injuries have seen an explosion of new knowledge. More precise imaging, correlative injury anatomy, more focused physical examination features, among others, have led this upsurge of current insight. Crucial to this knowledge revolution is the expansion of international knowledge, which is aided by an adoption of a universal scientific language, electronic transfer of information, and personal communication of surgeons and scientists across national boundaries. One area where this is particularly evident is in our knowledge and treatment for patellofemoral disorders. This article will review the developments in the management of patellar dislocations by tracing their historical roots. This is not meant to be a comprehensive review, but rather to give current readers a "historical memory" upon which to judge and interpret our present-day bridge of knowledge. Level of evidence V.

The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon

PURPOSE

Patellofemoral instability is influenced by ligamentous, boney and neuromuscular factors. The most important variables are trochlea geometry, medial patellofemoral ligament (MPFL), patella height, tibial tuberosity-trochlea groove distance (TT-TG) and the extensor muscles. Treatment is complicated by these multifactorial conditions. This prospective study examined the influence of risk factors on clinical results and athletic activities where treatment was confined to ligamentous procedures only.

METHODS

Fifty patients with chronic patellofemoral instability were treated with MPFL reconstruction using an autologous gracilis tendon. Clinical data, radiographs and magnetic resonance imaging (MRI) were prospectively evaluated pre- and postoperative (minimum follow-up 12 month) to detect existing risk factors for patellofemoral instability and to evaluate clinical and sport ability scores (Kujala, Valderrabano).

RESULTS

There was a low rate of redislocation (2 %) and an average Kujala score of 87 ± 13 points postoperative. The MRI showed good integration of the reconstructed MPFL and a positive effect regarding the decrease of patella tilt (16.1° to 11.2°). A negative relationship was found between the degree of trochlear dysplasia and outcomes. 80 % of all patients returned to the same or higher level of physical activity.

CONCLUSIONS

Addressing only ligamentous factors through MPFL reconstruction leads to satisfying clinical results and low redislocation rates in most patients. In cases with a high degree of trochlear dysplasia and enlarged TT-TG, additional procedures such as trochleaplasty and tibial tuberosity transfer should be considered as well.

LEVEL OF EVIDENCE

IV.

Lateral release and medial plication for recurrent patella dislocation

PURPOSE

This study aims to report the long-term results of lateral release and medial plication in patients with recurrent patellar dislocation.

METHODS

In this study, 31 patients who underwent surgery for recurrent patellar dislocation were retrospectively reviewed between 1994 and 2004. Among the 31 patients were 12 male and 19 female patients. The average age was 23.9 ± 4.8 years, and the mean follow-up period was 11.6 ± 2.4 years.

RESULTS

Three patients had postoperative dislocations. The mean Kujala score significantly improved from 57.5 ± 13.2 points preoperatively to 89.2 ± 8.7 points at the final follow-up (P < 0.0001). The median Tegner activity score significantly improved from 3 (range, 1-5) at preoperative examination to 7 (range, 3-9) at the final follow-up (P < 0.0001). Ten patients were rated as excellent, 18 as good, 2 as fair, and 1 as poor. The congruence angle improved from 16.5° ± 3.0° to -2.8° ± 2.7°, and the lateral patellofemoral angle improved from -4.2° ± 1.9° to 8.2° ± 2.5°. There was no case of osteoarthritis at the final follow-up.

CONCLUSIONS

Percutaneous lateral release and medial plication showed satisfactory results with limited morbidity in the long-term follow-up. This traditional method remains a simple and effective surgical procedure for recurrent patellar dislocation.

LEVEL OF EVIDENCE

Therapeutic, Level IV.

Modern management of patellar instability

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

A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation

BACKGROUND

Patellofemoral instability affects activities of daily living and hinders athletic participation. Over the past 2 decades, more attention has been paid to medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent patellar dislocations/subluxations. Numerous techniques have been reported; however, there is no consensus regarding optimal reconstruction.

PURPOSE

This study sought to report on the various techniques for MPFL reconstruction described in the literature and to assess the rate of complications associated with the procedure.

STUDY DESIGN

Meta-analysis.

METHODS

A systematic review of the literature was performed in early October 2010 using keywords "medial patellofemoral ligament," "MPFL," "reconstruction," "complication(s)," and "failure(s)." Articles meeting the inclusion criteria were reviewed. Graft choice, surgical technique, outcome measures, and complications were recorded and organized in a database. Descriptive statistical analysis was performed on the data collected.

RESULTS

Twenty-five articles were identified and reviewed. A total of 164 complications occurred in 629 knees (26.1%). These adverse events ranged from minor to major including patellar fracture, failures, clinical instability on postoperative examination, loss of knee flexion, wound complications, and pain. Twenty-six patients returned to the operating room for additional procedures.

CONCLUSION

Medial patellofemoral ligament reconstruction has a high rate of success for patients with patellofemoral instability; however, the complication rate of 26.1% associated with this procedure is not trivial. This study quantified complications and documented the variety of complications reported in outcomes-based literature.

The medial patellofemoral ligament: location of femoral attachment and length change patterns resulting from anatomic and nonanatomic attachments

BACKGROUND

Incompetence of the medial patellofemoral ligament (MPFL) is an integral factor in patellofemoral instability. Reconstruction of this structure is gaining increasing popularity. However, the natural behavior of the ligament is still not fully understood, and crucially, the correct landmark for femoral attachment of the MPFL at surgery is poorly defined.

PURPOSE

To determine the length change pattern of the native MPFL, investigate the effect of nonanatomic femoral and differing patellar attachment sites on length changes, and recommend a reproducible femoral attachment site for undertaking anatomic MPFL reconstruction.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eight cadaveric knees were dissected of skin and subcutaneous fat and mounted in a kinematics rig with the quadriceps tensioned. The MPFL length change patterns were measured for combinations of patellar and femoral attachments using a suture and displacement transducer. Three attachments were along the superomedial border of the patella, and 5 femoral attachments were at the MPFL center and 5 mm proximal, distal, anterior, and posterior to this point. Reproducibility of attachment sites was validated radiographically.

RESULTS

The femoral attachment point, taking the anterior-posterior medial femoral condyle diameter to be 100%, was identified 40% from the posterior, 50% from the distal, and 60% from the anterior border of the medial femoral condyle. This point was most isometric, with a mean maximal length change to the central patellar attachment of 2.1 mm from 0° to 110° of knee flexion. The proximal femoral attachment resulted in up to 6.4 mm mean lengthening and the distal attachment up to 9.1 mm mean shortening through 0° to 110° of knee flexion, resulting in a significantly nonisometric graft (P < .05).

CONCLUSION

We report the anatomic femoral and patellar MPFL graft attachments, with confirmation of the reproducibility of their location and resulting kinematic behavior. Nonanatomic attachments caused significant loss of isometry.

CLINICAL RELEVANCE

The importance of an anatomically positioned MPFL reconstruction is highlighted, and an identifiable radiographic point for femoral tunnel position is suggested for use intraoperatively.

The operative management of patella malalignment

Management of patellofemoral joint pathology is challenging as a result of the unique and complex organization of static forces and dynamic factors contributing to its functional capacity. Anterior knee pain is a common musculoskeletal complaint seen daily in the practices of primary care physicians, rheumatologists, and orthopedic surgeons. The key to successful treatment lies not only in the correct diagnosis of a chondral defect, but more importantly, in the accurate identification of associated pathomechanical factors. Appreciating the pathoanatomic basis of the disease and addressing imbalances and anatomical abnormalities should guide treatment.Despite the complexity of the interplay of various components it is essential to attempt to describe patellar malalignement as a clinical entity in order to proceed with appropriate surgical management and successful outcomes. The goals of patellofemoral re- alignment surgery should be to create both a stable environment for optimal extensor mechanism performance and an appropriate load transmission for optimal cartilage wear and joint loading. In the context of this article we will review the operative management of patellofemoral malalignment; the indications for surgery, the different techniques available and the evidence regarding their effectiveness.A large number of procedures have been employed and they have all undergone various modifications over the course of the years. The majority of publications are retrospective series in poorly defined population groups. There are significant methodological inconsistencies and as a result there is lack of strong evidence base for the majority of these procedures.

Arthroscopic extraarticular reconstruction of the medial patellofemoral ligament with gracilis tendon autograft - surgical technique

The standard approach to reconstruct the medial patellofemoral ligament (MPFL) is by mini-open incision at its patellar insertion and femoral origin. At the medial patella rim, the MPFL insertion may be visualized in most cases by dissection during surgery. On the femur, it is more difficult to localize the MPFL remnants by a mini-open incision due to soft tissue covering the anatomical origin. Therefore, the femoral MPFL origin is usually identified by intraoperative lateral fluoroscopy. However, the insertion and origin of the MPFL at the patella and femur might be directly visualized using an arthroscopic extraarticular approach from the knee joint through a window of the synovial layer. This is especially helpful on the femoral side but also at the patella to find the individual anatomical MPFL footprints. Arthroscopic extraarticular reconstruction may then be performed using one additional medial mid-parapatellar portal. The major advantages of this technique are an individualized anatomical procedure, which is minimal invasive and cosmetically appealing. The aim of this study was to describe the arthroscopic extraarticular approach to the MPFL insertion at the patella and origin at the femur through synovial windows and to explain the procedure of arthroscopic MPFL reconstruction with a gracilis tendon autograft. Level of evidence Expert opinion, surgical technique, Level V.

Complications of medial patellofemoral ligament reconstruction: common technical errors and factors for success: AAOS exhibit selection

BACKGROUND

The role of medial patellofemoral ligament reconstruction in reestablishing patellofemoral joint stability has recently been reported with increasing frequency. The purpose of this study was to review the reported complications of medial patellofemoral ligament reconstruction, highlight the common technical errors, and discuss the potential complications that can arise from this procedure.

METHODS

We review the literature on medial patellofemoral ligament reconstruction, including the reported causes of failure. In addition, we present three cases and discuss the multiple factors that are crucial for success, including patient selection, tunnel placement, graft isometry, and determination of the need for concurrent realignment surgery.

RESULTS

The principles of surgical management require a thorough understanding of proper patient selection and of the interaction between the roles of the osseous and soft-tissue restraints on the patella. Creating a logical treatment algorithm based on pathoanatomy can elucidate the need for concurrent distal realignment procedures. Tunnel positioning is critical in recreating appropriate patellofemoral alignment. The reported complications include patellofemoral arthrosis, graft impingement, and graft failure.

CONCLUSIONS

Many of the complications that can arise from medial patellofemoral ligament reconstruction are the result of technical error and can be avoided by understanding the potential complications associated with this procedure.

The role of medial retinaculum plication versus medial patellofemoral ligament reconstruction in combined procedures for recurrent patellar instability in adults

BACKGROUND

The comparative clinical outcome of medial retinaculum plication (MRP) versus medial patellofemoral ligament reconstruction (MPFLR) for recurrent patellar instability in adults is unknown.

HYPOTHESIS

Arthroscopic MRP can yield similar results to MPFLR for recurrent patellar instability in adults.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

One hundred patients with recurrent patellar instability were randomly divided into 2 groups receiving either arthroscopic MRP or MPFLR. Lateral release and anteromedial or distal tibial tubercle transfers were also performed as indicated. Follow-ups were performed at 12, 24, and 60 months postoperatively, and computed tomography (CT) was performed immediately after the operation and at follow-up. The passive patella glide test was performed before surgery and at each follow-up point. The degree of knee function was evaluated preoperatively and at 2 and 5 years postoperatively using the International Knee Documentation Committee (IKDC), Lysholm, and Kujala rating scales. Survival analysis was performed, and redislocation or multiple episodes of patellar instability were considered as indicating failure.

RESULTS

Forty-three patients in the MRP group and 45 patients in the MPFLR group were followed for 5 years and received complete evaluations. The correction of the static patellar position deteriorated over time in both groups, but significantly better results were observed for the MPFLR group. The results of the passive patella glide test indicated more stable patellae in the MPFLR group at each follow-up point. Functional evaluations at 2 and 5 years (final Lysholm score, 69.3 ± 6.9 vs 86.9 ± 6.1; Kujala score, 73.8 ± 5.5 vs 87.4 ± 5.7) revealed statistically significant superior results in the MPFLR group. Finally, 4 patients (9.3%) in the MRP group and 1 (2.2%) in the MPFLR group experienced episodes of redislocation, and 7 patients (16.3%) in the MRP group and 3 (6.7%) in the MPFLR group experienced multiple episodes of patellar instability (P = .037). Kaplan-Meier survival analysis and a log-rank test indicated better results and a significantly higher survival rate (P = .006) in the MPFLR group.

CONCLUSION

MPFLR results in better static patellar position and functional outcome than MRP in the treatment of recurrent patellar dislocation in adults.

Reconstruction of the medial patellofemoral ligament using the adductor magnus tendon: an anatomic study

PURPOSE

The aims of this study were to evaluate the anatomic feasibility of medial patellofemoral ligament (MPFL) reconstruction using a part of the adductor magnus tendon and to identify possible risks.

METHODS

Twenty cadaveric knees were dissected. The distal part of the adductor magnus tendon was evaluated with respect to the anatomic topography and its utility for MPFL reconstruction. To estimate the risk of injuring the neurovascular structures, the distance from the adductor tubercle to the adductor hiatus was evaluated. An MPFL reconstruction was carried out by preserving the distal insertion on the adductor tubercle and redirecting the proximal portion of the tendon to the medial aspect of the patella.

RESULTS

The anatomic investigation showed the following relationships: The mean distance from the adductor tubercle to the adductor hiatus was 99 ± 14 mm (range, 80 to 120 mm). A graft length of 52 ± 5 mm (range, 45 to 63 mm) with the addition of 10 to 20 mm for fixation was found to be necessary for MPFL reconstruction. The difference between the desired graft length and the distance to the adductor hiatus was found to be at least 30 mm in all cases (mean, 46 mm). Leaving the graft attached to the adductor tubercle resulted in a nearly anatomic femoral attachment of the reconstructed MPFL. Complete detachment of the distal adductor magnus attachment was consistently avoidable.

CONCLUSIONS

The adductor magnus tendon was found to be a useful graft for MPFL reconstruction. However, anatomic dangers (damage to the neurovascular bundle of the adductor hiatus, the saphenous nerve, or the saphenous branch of the descending genicular artery) during graft harvest must be considered.

CLINICAL RELEVANCE

Anatomic knowledge is essential during adductor magnus tendon harvest to avoid damage to neurovascular structures. The adductor magnus tendon is an interesting alternative graft option for MPFL reconstruction if anatomic dangers are considered and avoided.

Trochleoplasty and medial patellofemoral ligament reconstruction for recurrent patellar dislocation

We report a case of recurrent patellar dislocation with high-grade trochlear dysplasia which persisted despite two previous operations. We did a Dejour's sulcus deepening trochleoplasty, medial patellofemoral ligament reconstruction, and lateral retinacular release. Trochleoplasty and medial patellofemoral ligament reconstruction is required in patients with high grade trochlear dysplasia.

Reconstruction of medial patellofemoral ligament for chronic patellar instability

BACKGROUND

Disruption of the capsule, medial patellar retinaculum, and/or vastus medialis obliqus has been associated with recurrent patellar instability. Biomechanical studies have shown that the medial patellofemoral ligament (MPFL) is the main restraint against lateral patella displacement and reconstruction of the MPFL has become an accepted surgical technique to restore patellofemoral stability in patients having recurrent patellar dislocation. We report a prospective series of patients of chronic patellar instability treated by reconstruction of medial patellofemoral ligament.

MATERIALS AND METHODS

Twelve patients (15 knees) with recurrent dislocation of patella, were operated between January 2006 and December 2008. All patients had generalised ligament laxity with none had severe grade of patella alta or trochlear dysplasia. The MPFL was reconstructed with doubled semitendinosus tendon. Patients were followed up with subjective criteria, patellar inclination angle, and Kujala score.

RESULTS

The mean duration of followup after the operative procedures was an average of 42 months (range 24-60 months) 10 knees showed excellent results, 3 knees gave good results, and 2 knees had a fair result. The average patellar inclination angle decreased from 34.3° to 18.6°. The average preoperative Kujala functional score was 44.8 and the average postoperative score was 91.9.

CONCLUSION

MPFL reconstruction using the semitendinosus tendon gives good results in patients with chronic patellar instability without predisposing factors like severe patella alta and high-grade trochlear dysplasia, and for revision cases.

Medial patellofemoral ligament reconstruction with a divergent patellar transverse 2-tunnel technique

BACKGROUND

The medial patellofemoral ligament (MPFL) is the primary passive restraint to lateral patellar dislocation and there is increasing awareness of its role in recurrent lateral patellar instability.

PURPOSE

This study was conducted to prospectively analyze the functional results of a modified MPFL reconstruction technique in recurrent patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Forty-eight patients (51 knees) with at least 3 episodes of lateral patellar dislocation who had been treated with a 6-month rehabilitation protocol were included in this study. All patients practiced sports regularly. Reconstruction was with a semitendinosus tendon using a divergent 2-tunnel technique. Outcome was evaluated with the Kujala, Larsen, modified Lysholm, and Fulkerson outcome scores. Patient satisfaction with range of motion, pain, and sporting activities was also assessed.

RESULTS

Three patients were lost at the final follow-up, giving a follow-up rate of 94%. The mean follow-up was 33 months. There was no patella dislocation postoperatively. The mean Kujala score improved significantly (P < .01) from 56.7 ± 17.7 (2 × standard deviation) preoperatively to 86.8 ± 14.4 postoperatively. The mean Larsen score improved significantly (P < .01) from 12.4 ± 3.2 to 17.1 ± 2.7. The mean Fulkerson score improved significantly (P < .01) from 59.2 ± 21.8 to 90.1 ± 14. The mean modified Lysholm score improved significantly (P < .01) from 57.6 ± 19.6 to 88.1 ± 16.2. Sixty-four percent of patients returned to the same type of sport at the same level, 16% reduced the level or type of sport for reasons unrelated to the surgery, while 20% reduced the level of sport or changed it for reasons related to surgery. Eighty-seven percent were either satisfied or very satisfied with the pain relief achieved. The patellar tilt decreased significantly from a preoperative mean of 11.1° to 8.9° at the last follow-up (P = .02). The mean preoperative Insall-Salvati ratio of 1.1 decreased to 1.06, although the change was not significant (P = .1).

CONCLUSION

The results of modified MPFL reconstructions are encouraging, with minimal risks of redislocation and an overall patient satisfaction rate of over 80%. These early and medium-term results are comparable with those of other MPFL reconstruction techniques reported in the literature.

[Treatment of patellar instability in children and adolescents]

To address recurrent patellar instability in children and young adolescents a variety of therapeutic options exist either as non-operative or operative treatment. Recent options, such as reconstruction of the medial patellofemoral ligament have evoked a new focus of attention on this topic. The intention of this article is to present diverse therapeutic options and to evaluate them by reference to the current literature.

Gracilis tendon transfer associated with distal alignment for patella alta with recurrent dislocations: an original surgical technique

Many surgical techniques for the medial patellofemoral ligament have recently been suggested, all of which included problems identifying the femoral anchorage point and determining the proper extent of knee flexion for the transplant. P. Burdin proposed a different and original approach consisting in performing a gracilis muscle transfer to the medial edge of the patella, thus obtaining progressive tension of the transfer during knee flexion by means of the myotatic reflex. We report the results herein. We retrospectively assessed 17 knees treated for patellofemoral instability using this technique. Two cases presented subjective patellofemoral instability and 15 presented objective patellofemoral instability. The patients' mean age was 17.4 years (range, 8-47 years) during the first episode of dislocation. Two cases of instability were secondary to advanced neuromuscular disease. Two knees had already undergone two stabilization attempts. Fifteen knees presented trochlear dysplasia (four stage A, eight stage B, and three stage C). The mean age at surgery was 28.2 years (range, 16-47 years). In 15 cases, the gracilis transfer was associated with lowering the anterior tibial tuberosity (mean, 10mm). No patellar fracture occurred. A persistent sensory deficit of the anterior branch of the internal saphenous nerve was observed in 15 cases. One knee remained painful and retained subjective instability; total knee arthroplasty was performed 3 years after the intervention. The mean follow-up at revision was 5.5 years (range, 1.5-16.5 years). No recurrence of dislocation was reported. Eight cases retained subjective instability. The SF-36 and IKDC scores were good or excellent in 12 cases and the KOOS was good or excellent in 13 cases. Radiologically, patellar tilt persisted in six cases out of 14, translation persisted in two cases out of 14, and secondary patella baja was observed in one. Medial patellofemoral osteoarthritis was observed in five cases: one case IWANO stage I and four cases IWANO stage II. These satisfactory results seem stable over time and were acquired using a simple procedure with reduced morbidity, making it possible to avoid significant displacement of the anterior tibial tuberosity and stabilize the extensor apparatus. It can also be hoped that the onset of secondary patellofemoral osteoarthritis, undoubtedly inevitable, has been delayed.

The role of trochlear dysplasia in patellofemoral instability

Trochlear dysplasia is characterized by abnormal trochlear morphology and a shallow groove. It is associated with recurrent patellar dislocation, but it is unclear whether the dysplasia is congenital, the result of lateral tracking and chronic instability, or caused by a combination of factors. Lateral radiographs elucidate the crossing sign and characteristic trochlear prominence. Recurrent patellofemoral instability is multifactorial, and each component must be considered in determining treatment. Managing other factors associated with recurrent instability may compensate for a deficient trochlea and provide stability. Medial patellofemoral ligament reconstruction is recommended for patellofemoral instability in the presence of trochlear dysplasia in patients without patella alta or increased tibial tubercle-trochlear groove distance. Trochleoplasty should be reserved for severe dysplasia in which patellofemoral stability cannot otherwise be obtained.

Medial patellofemoral ligament reconstruction fixed with a cylindrical bone plug and a grafted semitendinosus tendon at the original femoral site for recurrent patellar dislocation

BACKGROUND

The medial patellofemoral ligament (MPFL) is the most important factor for stabilizing the patella and preventing lateral patellar dislocation. Medial patellofemoral ligament reconstruction is an accepted surgical technique to restore patellofemoral stability after lateral patellar dislocation. The authors recently developed a new anatomical MPFL reconstruction method using a cylindrical bone plug and grafted semitendinosus tendon at the anatomical femoral attachment site to mimic the native MPFL. This study evaluated the new technique for stabilizing recurrent patellar dislocation.

HYPOTHESIS

This new MPFL reconstruction technique will improve knee symptoms and function with excellent clinical results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHOD

Thirty-one knees were evaluated from 29 cases of recurrent patellar dislocation that were surgically treated using the anatomical MPFL reconstruction technique. The average patient age was 22.2 years (range, 12-34 years); postsurgery follow-up was 2 to 5 years (average, 3.2 years). The patients were clinically evaluated based on the Kujala score, range of motion, and signs of apprehension. The Merchant view was used to measure congruence and tilting angles.

RESULTS

Of the 31 knees, 30 showed good clinical results after surgery, while 1 patient showed remaining signs of apprehension. The Kujala score improved from an average of 64 points (range, 35-70) initially to an average of 94.5 points (range, 79-100) at the final follow-up. Range of motion improved for all patients, with an average knee extension of 0° ± 2° and knee flexion of 145° ± 3° at final follow-up. No patellar redislocation was reported. Radiological assessment indicated significant improvement to the congruence angle from 13° ± 4° before surgery to -5° ± 5° at the final follow-up, while the tilting angle went from 8° ± 7° before surgery to 7° ± 4° at the final follow-up.

CONCLUSION

This study demonstrated excellent results using the new procedure for recurrent dislocation of the patella, with instability in only 1 of 31 knees (3.2%).

In vivo positioning analysis of medial patellofemoral ligament reconstruction

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

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

RESULTS

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

CONCLUSION

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

Medial patellofemoral ligament repair for recurrent patellar dislocation

BACKGROUND

The medial patellofemoral ligament (MPFL) is the primary restraint to extreme lateral displacement and is typically disrupted with an acute lateral patellar dislocation. Patients who fail a comprehensive nonoperative program and experience recurrent lateral patellar instability episodes are candidates for surgical treatment. Current surgical procedures include a variety of proximal realignment techniques, including repair or reconstruction of the MPFL along with distal realignment of the tibial tubercle when indicated.

PURPOSE

The objective of this study was to review the clinical, functional, and radiographic outcomes of isolated MPFL repair for recurrent lateral patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The records of all patients undergoing MPFL repair for recurrent patellar dislocation at the Mayo Clinic from 2001 to 2006 were retrospectively reviewed. Twenty-seven patients (29 knees) with an average age of 19 years (range, 11-32 years) were included in this study. Clinical, functional, and radiographic outcomes were assessed at an average of 4 years after surgery (range, 2-7 years), using recurrent instability as the primary end point.

RESULTS

The success rate of MPFL repair for preventing recurrent dislocations was 72% (21 of 29 knees). Eight patients (28%) experienced a recurrent lateral patellar dislocation. Five of these patients required a reoperation, including two MPFL reconstructions, 1 tibial tubercle osteotomy with MPFL reconstruction, 1 tibial tubercle osteotomy with revision MPFL repair, and 1 revision MPFL repair. At final follow-up, the mean Lysholm and Kujala scores were 86 (range, 42-100) and 92 (range, 57-105), respectively. Postoperative radiographs revealed a mean patellofemoral congruence angle improvement of 27° (range, 5°-44°). The only statistically significant risk factor for failure was nonanatomical MPFL repair at the medial femoral condyle (P = .004).

CONCLUSION

Isolated repair of the MPFL for recurrent patellar instability is associated with a relatively high failure rate, but remains a viable surgical option if surgical technique principles are followed. The clinical success of this operation depends on restoration of the anatomical origin of the MPFL and careful patient selection.

Medial patellofemoral ligament reconstruction for recurrent patellar dislocation: a systematic review including rehabilitation and return-to-sports efficacy

PURPOSE

We systematically reviewed the evaluated efficacy of medial patellofemoral ligament (MPFL) reconstruction, rehabilitation, and patient outcomes for safely returning patients to sports.

METHODS

We performed a literature search using the Ovid Medline database from 1950 to present, as well as the SportDiscus and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases. Only English-language studies that described MPFL reconstruction or repair, rehabilitation, and patient outcome information were included. Search terms were combinations of "MPFL repair," "MPFL reconstruction," "patellofemoral ligament," "patellar dislocation," "patient outcome," and "rehabilitation." Coleman Methodology Scores were used to evaluate research quality.

RESULTS

A total of 21 studies (11 prospective and 10 retrospective) met our inclusion criteria, with a total of 488 patients (184 male and 304 female patients) and 510 knees contributing to this review. Most patients were female (62.3%), and the mean age at surgery was 23.4 years (range, 6 to 52 years). Semitendinosus autografts were most commonly used (n = 145 [28.4%]). Of all reported complications at follow-up (n = 155), quadriceps dysfunction (n = 48 [31.0%]), positive apprehension (n = 32 [20.6%]), and decreased knee range of motion (n = 28 [18.1%]) were most common. Although inclusion criteria required rehabilitation information, the level of description was generally limited to acute care rehabilitation, with insufficient progressive exercise descriptions. Coleman Methodology Scores (58.76 ± 8.6) indicated generally poor study methodologies.

CONCLUSIONS

MPFL reconstruction and rehabilitation are likely to improve a patient's ability to perform activities of daily living. Poor study methodology including outcome surveys that lack either sensitivity or validity to measure the influence of patellofemoral joint dysfunction on sports participation, as well as limited exercise rehabilitation information, make it difficult to determine efficacy. Recommendations for improved outcome measurements and more comprehensive functional rehabilitation are provided.

LEVEL OF EVIDENCE

Level IV, systematic review.

The associations between indices of patellofemoral geometry and knee pain and patella cartilage volume: a cross-sectional study

Background

Whilst patellofemoral pain is one of the most common musculoskeletal disorders presenting to orthopaedic clinics, sports clinics, and general practices, factors contributing to its development in the absence of a defined arthropathy, such as osteoarthritis (OA), are unclear.

The aim of this cross-sectional study was to describe the relationships between parameters of patellofemoral geometry (patella inclination, sulcus angle and patella height) and knee pain and patella cartilage volume.

Methods

240 community-based adults aged 25-60 years were recruited to take part in a study of obesity and musculoskeletal health. Magnetic resonance imaging (MRI) of the dominant knee was used to determine the lateral condyle-patella angle, sulcus angle, and Insall-Salvati ratio, as well as patella cartilage and bone volumes. Pain was assessed by the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) VA pain subscale.

Results

Increased lateral condyle-patella angle (increased medial patella inclination) was associated with a reduction in WOMAC pain score (Regression coefficient -1.57, 95% CI -3.05, -0.09) and increased medial patella cartilage volume (Regression coefficient 51.38 mm³, 95% CI 1.68, 101.08 mm³). Higher riding patella as indicated by increased Insall-Salvati ratio was associated with decreased medial patella cartilage volume (Regression coefficient -3187 mm³, 95% CI -5510, -864 mm³). There was a trend for increased lateral patella cartilage volume associated with increased (shallower) sulcus angle (Regression coefficient 43.27 mm³, 95% CI -2.43, 88.98 mm³).

Conclusion

These results suggest both symptomatic and structural benefits associated with a more medially inclined patella while a high-riding patella may be detrimental to patella cartilage. This provides additional theoretical support for the current use of corrective strategies for patella malalignment that are aimed at medial patella translation, although longitudinal studies will be needed to further substantiate this.

Reconstruction of the medial patellofemoral ligament for treatment of patellofemoral instability: a systematic review

BACKGROUND

Growing awareness of the biomechanical contribution of the medial patellofemoral ligament 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.

STUDY DESIGN

Systematic review.

METHODS

The authors undertook a systematic electronic search and rigorous screening process to find and identify published evidence describing the outcomes of medial patellofemoral ligament reconstruction.

RESULTS

Fourteen trials were included for analysis. Although they showed generally excellent outcomes for medial patellofemoral ligament reconstruction modalities, there were several recurring weaknesses. Most were small case series, many had limited follow-up, and a majority employed other adjunctive techniques besides medial patellofemoral ligament reconstruction, making it difficult to distinguish the determining factors in their outcomes.

CONCLUSION

There is limited but growing evidence that a medial patellofemoral ligament-based surgical approach to patellofemoral instability leads to excellent functional outcomes.

Reconstruction of the medial patellofemoral ligament using a longitudinal patellar tunnel technique

Patellar instability is a common clinical problem affecting a young, active population. A large number of procedures have been described to treat patellar instability. We present the clinical results in a case series of 25 medial patellofemoral ligament reconstructions in 21 patients with up to 30 months follow-up (mean: 7.3). Reconstruction was performed using either the gracilis or semitendinosus tendon autograft. The Tegner activity score improved overall from 3 to 4.4 at follow-up and the mean follow-up Kujala score was 87 (range: 55-100). No patella redislocations were observed. Five patients (20%) required a manipulation under anaesthetic but subsequently regained a satisfactory range of motion. Medial patellofemoral reconstruction with both gracilis and semitendinosus tendon graft using a longitudinal tunnel technique provided good post-operative stability restoring the primary soft tissue restraint to pathological lateral patellar displacement with no complications of post-operative patellar fracture.

Isolated medial patellofemoral ligament reconstruction for recurrent patellar dislocation

BACKGROUND

Several medial patellofemoral ligament reconstruction procedures have been proposed to manage recurrent patellar dislocation.

HYPOTHESIS

Reconstruction of the medial patellofemoral ligament using a hamstring graft with a 2 transverse patellar tunnels technique is an effective treatment for recurrent patellar dislocation in patients without any evident predisposing factors.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-eight patients with chronic patellar instability without any anatomic predisposing factors, experiencing recurrent unilateral patellar dislocation, were included in the study. Evaluation included the modified Cincinnati and the Kujala scores, anthropometry, plain radiography, and isokinetic dynamometry.

RESULTS

The average follow-up was 3.1 years (range, 2.5-4 years). The mean modified Cincinnati score increased from 52 preoperatively to 89 (P = .001). The mean Kujala scores increased from 45 preoperatively to 83 (P = .03). The muscle volume of the thigh of the operated limb increased with time, but remained less well developed than the nonoperated limb (P = .04). The mean Insall-Salvati index was 1.1 (range, 0.9-1.2) preoperatively and remained within normal range (1.1 [range, 0.9 to 1.2]) (P = .07), at latest follow-up. Significant isokinetic strength differences were found between the operated and the contralateral limbs (.05 < P < .006), even at the latest follow-up. Three patients experienced a new patellar dislocation.

CONCLUSION

Medial patellofemoral ligament reconstruction using hamstring tendon passed through a double patellar transverse bony tunnel technique is a safe, reliable management option for recurrent patellar dislocation in patients without any predisposing anatomic factors.

Surgical correction of limb malalignment for instability of the patella: a comparison of 2 techniques

BACKGROUND

Although patients considered "successful" at longer-term follow-up no longer exhibited patellar instability, those with more severe malalignment issues had other, gradually worsening symptoms such as activity-related pain, crepitation, swelling with activities, and pain with weather changes.

HYPOTHESIS

Improvement of patellar tracking by correction of the tubercle-sulcus angle and related ligament deficiencies will result in good to excellent results, regardless of the technique employed.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Twenty-five patients with dislocating patellae and significant lower leg deformity were treated; 12 patients (group 1) underwent a derotational high tibial osteotomy and 13 patients (group 2) underwent an Elmslie-Trillat-Fulkerson proximal-distal realignment. All were prospectively evaluated a minimum of 24 months postoperatively with a physical examination, validated outcome questionnaires, radiographs, and computerized axial tomography scans. Postoperative 3-dimensional bilateral gait analyses were performed on all subjects walking on a 3-dimensional force treadmill to measure stance kinematics, foot progression angle, knee flexion, knee valgus-varus, hip flexion, and patella angle. Contralateral limbs with similar preoperative alignment were used as controls.

RESULTS

Group 1 patients significantly improved over their preoperative status in all primary subjective and functional outcome parameters, and were significantly better than group 2 patients. Group 2 patients improved, but not to the degree of group 1 patients. Gait analysis revealed group 1 patients had more symmetrical gait patterns, with less variability and less compensatory gait changes, than group 2 patients.

CONCLUSION

The original hypothesis proved to be incorrect. The simultaneous correction of ligament imbalance, excessive tubercle-sulcus angle, and lower limb torsional deformity produced significantly better results than conventional proximal-distal realignment.

Improving vastus medialis obliquus function reduces pressure applied to lateral patellofemoral cartilage

The current study was performed to characterize how improving vastus medialis obliquus (VMO) function influences the pressure applied to patellofemoral cartilage. An additional focus was characterizing how lateral and medial cartilage lesions influence cartilage pressures. Ten knees were flexed to 40 degrees, 60 degrees, and 80 degrees in vitro, and forces were applied to represent the VMO and other muscles of the quadriceps group while a thin film sensor measured joint pressures. The knees were loaded with a normal VMO force, with the VMO force decreased by approximately 50%, and with the VMO unloaded. After tests were performed with the cartilage intact, all tests were repeated with a 12-mm-diameter lesion created within the lateral cartilage, with the lateral lesion repaired with silicone, and with a medial lesion created. Based on a two-way repeated measures ANOVA and post-hoc tests, increasing the force applied by the VMO significantly (p < 0.05) decreased the maximum lateral pressure and significantly increased the maximum medial pressure at each flexion angle. A lateral cartilage lesion significantly increased the maximum lateral pressure, while a medial lesion did not significantly influence the maximum medial pressure. Improving VMO function can reduce the pressure applied to lateral cartilage when lateral lesions are present.

A mini-invasive adductor magnus tendon transfer technique for medial patellofemoral ligament reconstruction: a technical note

Patellar dislocations are associated with injuries to the medial patellofemoral ligament (MPFL). Several techniques for MPFL reconstruction have been recently published with some disadvantages involved, including large skin incisions and donor site morbidity. Arthroscopic stabilizing techniques carry the potential of inadequate restoration of MPFL function. We present a minimally invasive technique for MPFL reconstruction using adductor magnus tendon autograft. This technique is easily performed, safe, and provides a stabilizing effect equal to current MPFL reconstructions. Skin incision of only 3-4 cm is located at the level of the proximal half of the patella. After identifying the distal insertion of the adductor magnus tendon, a tendon harvester is introduced to harvest the medial two-thirds of the tendon, while the distal insertion is left intact. The adductor magnus tendon is cut at 12-14 cm from its distal insertion and transferred into the patellar medial margin. Two suture anchors are inserted through the same incision at the superomedial aspect of the patella in the anatomic MPFL origin. The graft is tightened at 30 degrees knee flexion. Aftercare includes 4 weeks of brace treatment with restricted range of motion.

Patellar instability

Recurrent patellar instability can result from osseous abnormalities, such as patella alta, a distance of >20 mm between the tibial tubercle and the trochlear groove, and trochlear dysplasia, or it can result from soft-tissue abnormalities, such as a torn medial patellofemoral ligament or a weakened vastus medialis obliquus. Nonoperative treatment includes physical therapy, focusing on strengthening of the gluteal muscles and the vastus medialis obliquus, and patellar taping or bracing. Acute medial-sided repair may be indicated when there is an osteochondral fracture fragment or a retinacular injury. The recent literature does not support the use of an isolated lateral release for the treatment of patellar instability. A patient with recurrent instability, with or without trochlear dysplasia, who has a normal tibial tubercle-trochlear groove distance and a normal patellar height may be a candidate for a reconstruction of the medial patellofemoral ligament with autograft or allograft. Distal realignment procedures are used in patients who have an increased tibial tubercle-trochlear groove distance or patella alta. The degree of anteriorization, distalization, and/or medialization depends on associated arthrosis of the lateral patellar facet and the presence of patella alta. Associated medial or proximal patellar chondrosis is a contraindication to distal realignment because of the potential to overload tissues that have already undergone degeneration.

Comparison between a static and a dynamic technique for medial patellofemoral ligament reconstruction

PURPOSE

The purpose of our study was to compare the technical difficulties and the results of the use of two different types of femoral graft fixation for medial patellofemoral ligament reconstruction in patients with patellar luxation.

METHODS

Twenty-four matched pair patients, assigned to two groups of 12 patients each, underwent medial patellofemoral ligament reconstruction using one of two techniques: the adductor magnus rigid and the semitendinosus tendon dynamic femoral fixation. Results were assessed using a scale for activities of daily living before and after surgery.

RESULTS

No statistical difference was detected between the groups despite one case of reluxation in the adductor magnus group. No major complication was observed in either group. Patients in the semitendinosus group felt subjectively better, and a larger number of patients in this group resumed the practice of sports.

CONCLUSIONS

Even in the absence of significant differences, the present results suggest that a more dynamic femoral fixation is more advantageous than a rigid alternative.

LEVEL OF EVIDENCE

Level III, therapeutic comparative study.

The effects of trochlear groove geometry on patellofemoral joint stability-a computer model study

The effect of the variation in the femoral groove geometry on patellofemoral joint stability was studied using a two-dimensional transverse plane model with deformable articular surfaces. The femoral and patellar bony structures were modelled as rigid bodies with their profiles expressed by splines. The articular cartilage was discretized into compression springs, distributed along the femoral and patellar profiles, based on the rigid-body spring model. The medial and lateral retinacula were modelled as linear tensile springs, and the quadriceps muscles and patellar tendon as strings with known tension. The anatomical data were obtained from the transverse plane magnetic resonance images of a normal knee flexed at 20° and from the literature. A dynamic analysis approach was employed to solve the governing equations of the model, i.e. three static equilibrium equations of the patella and a constraint equation for each cartilage spring, explicitly. The results of the model suggest that alteration of the sulcus angle from 139° to 169° causes a lateral shift and tilt of less than 3 mm and 4°. This effect increased slightly with increasing total quadriceps force, however, to significantly more than 7 mm and 18° respectively when the medial retinaculum was released. It was suggested that this might be the combined effect of the medial retinaculum deficiency and trochlear dysplasia that is responsible for patellar subluxation and, particularly, dislocation disorders.

Reconstruction of the medial patellofemoral ligament with gracilis tendon autograft in transverse patellar drill holes

PURPOSE

We present clinical results in a case series of 44 patients with medial patellofemoral ligament (MPFL) reconstruction with 12 to 32 months' follow-up.

METHODS

Reconstruction was performed via gracilis tendon autograft looped through 2 transverse 4.5-mm drill holes in the patella and fixed at the natural MPFL insertion site on the medial femoral condyle with an interference screw. At follow-up, Kujala scores, Knee Injury and Osteoarthritis Outcome Scores, objective knee function, complications, and reoperations were assessed.

RESULTS

Only 1 patella redislocation was observed. Subluxation occurred in 3 patients, whereas 4 patients had chronic pain at follow-up, all of whom had cartilage injury at surgery. The Kujala knee function score improved overall from 46 points (range, 12 to 67 points) to 84 points (range, 62 to 100 points) at follow-up.

CONCLUSIONS

MPFL reconstruction with double transverse patella drill holes and a gracilis tendon graft provides good postoperative patellar stability. Postoperative pain seems to be related to the degree of patellofemoral injury found at surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.