The case for advancement and repairof the medial patellofemoral ligament in patients with recurrent patellar instability

Arthroscopic patellar reinsertion of the MPFL in acute patellar dislocations

PURPOSE

The objective of this study was to evaluate the mid-term results of a new technique for the arthroscopic repair of MPFL after an acute patellar dislocation (APD).

MATERIALS

The series included 17 patients (11 men and 6 women) with a first episode of acute patellar dislocation; treated over a period of 6 years. Re-dislocation, subjective symptoms and functional limitations were evaluated at an average follow-up of 2.2 years (1-5.5). The patients were evaluated with the Lysholm and the Kujala scoring systems.

RESULTS

At follow-up, no re-dislocation was reported. Only one patient referred an episode of patellar instability, without a distinct dislocation. The postoperative median Lysholm score was 90 (72-100). The median Kujala score was 92 (75-100). Fourteen out of 17 patients were able to return to sports at the same level as before.

CONCLUSION

When the MPFL is avulsed from the patella, the proposed technique has the advantage of restoring tension of the ligament through reattachment at the patellar border with two trans-patellar sutures. The full-arthroscopic approach has the advantage of being less invasive and having a shorter recovery time.

The medial patellofemoral ligament

There has been substantial progress in our understanding of the medial patellofemoral ligament during the past 10 years. This structure is the primary static soft-tissue restraint to lateral patellar displacement. Substantial alteration of normal patellar tracking occurs after sectioning of the ligament. Clinical studies have demonstrated the medial patellofemoral ligament is disrupted during acute patellar dislocation. Recently, several medial patellofemoral ligament-based procedures have been developed for the treatment of patellar instability with good early results. However, further studies are needed to define the exact role of these procedures in the treatment of patellofemoral instability.

Comparison of isometric and anatomic reconstruction of the medial patellofemoral ligament: a cadaveric study

Recent surgical procedures designed to correct recurrent posttraumatic lateral patellar instability focus on reconstructing the medial patellofemoral ligament. This study evaluated and compared patellofemoral kinematics of isometric and anatomic medial patellofemoral ligament reconstructions. Using an infrared motion capture analysis system, patellar tracking was evaluated in the coronal plane in 6 cadaveric specimens. Reconstruction of the medial patellofemoral ligament using an isometric technique did not restore normal patellar tracking at any flexion angle; however, reconstruction using an anatomic technique restored statistically normal patellar tracking from maximal knee extension to 28 degrees of flexion. Neither technique was able to restore normal kinematics in deeper angles of knee flexion.

Reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft: a case series

This study assessed medial patellofemoral ligament reconstruction using a partial-thickness quadriceps tendon graft in 14 knees in 13 patients. Nine patients were available for follow-up after a minimum of 24 months. Final patient evaluation was performed an average of 42 months postoperatively (range, 28-65 months). Primary outcome measure was occurrence of patellar dislocation postoperatively, and outcomes were quantified using the Kujala questionnaire and Crosby and Insall criteria. Postoperatively, no patient reported patellar dislocation. Using Crosby and Insall criteria, good or excellent results were achieved in 100% of patients. Mean Kujala score was 91.9. Postoperatively, all patients reported their knee was improved. These findings indicate medial patellofemoral ligament reconstruction with a quadriceps tendon graft is effective in preventing patellar dislocation and improving quality of life. However, patients should be counseled this procedure is indicated primarily for the treatment of recurrent instability, and postoperative relief of anterior knee pain is inconsistent.

LEVEL OF EVIDENCE

Level IV, Case Series.

Combined proximal and distal realignment procedures to treat the habitual dislocation of the patella in adults

BACKGROUND

Habitual dislocation of the patella (HDP) is a rare condition. Many surgical procedures using proximal realignment have been reported to treat HDP in children, with around 80% satisfactory results. However, few articles have addressed the treatment of HDP associated with high-grade patellofemoral chondromalacia in adults.

HYPOTHESIS

A combination of proximal and distal realignment procedures of the patella will reduce pain and increase function in adult patients with HDP.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twelve patients with 13 symptomatic cases of HDP of the knee underwent surgical treatment that included lateral release, medial retinaculum advancement, and the anteromedial tibial tubercle transfer procedure. The average period between dislocation and surgery was 10.8 years. One patient had an additional procedure, an open-wedge varus corrective osteotomy of the distal femur, because of a 20 degrees valgus deformity of the knee. The patellofemoral morphology study included routine and Merchant views of the knee and a computed tomography scan at full extension and at 30 degrees flexion of the knee, before the operation and at follow-up. Any associated intra-articular pathologic findings during the surgical procedure were addressed. Patellofemoral function was evaluated with the Kujala functional score before surgery and at the time of the final follow-up.

RESULTS

Chondromalacia of the patella over the medial facet and central ridge was grade III in 8 knees and grade IV in 5 knees. Corresponding chondral erosion of the lateral femoral condyle was noted in every knee. All patients were followed for an average period of 67.3 months (range, 25-103 months). The average preoperative Kujala functional score was 43.9 and the average postoperative score was 88.9 (P< .05). Radiographically, there was a statistically significant improvement in the congruence angle from 62.1 degrees +/- 15.0 degrees preoperatively to -2.7 degrees +/- 9.8 degrees postoperatively (P< .01) and in the lateral patellofemoral angle from -40.2 degrees +/- 9.3 degrees preoperatively to 1.4 degrees +/- 7.0 degrees postoperatively (P< .01). No patient has reported an episode of patellar dislocation after the surgical procedures.

CONCLUSION

Combined proximal and distal realignments of the patella effectively treat HDP in adults with associated high-grade patellofemoral chondromalacia.

The role of autologous chondrocyte implantation in the patellofemoral joint

In a prospective study to determine the clinical effectiveness of autologous chondrocyte implantation, 45 patients reached a minimum followup of 2 years (range, 2-7 years; average, 46.4 months) after treatment involving the patellofemoral articulation. There were 28 men (61%) and 17 women (39%) and the average age of the patients was 37.5 years (range, 15-55 years). The treatment groups included (I) isolated patella, n = 8; (II) isolated trochlea, n = 9; (III) patella plus trochlea, n = 4; (IV) weightbearing condyle plus patella n = 2; (V) weightbearing condyle plus trochlea, n = 2; and (VI) weightbearing condyle plus patella plus trochlea n = 20. The average surface area per patella (n = 34) was 4.86 cm2 and per trochlea (n = 34) it was 5.22 cm2. The average resurfacing per knee (n = 45) was 10.45 cm2. We showed a postoperative improvement in quality of life as measured by the Short Form-36; Western Ontario and McMaster University Score, Knee Society Score, modified Cincinnati Score, and a patient satisfaction survey. There were eight failures (18%) as a result of a patella or trochlea failure. Seventy-one percent of patients rated their outcomes as good or excellent, 22% rated outcome as fair, and 7% rated outcome as poor.

LEVEL OF EVIDENCE

Therapeutic Study, Level II-1 (prospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

Epidemiology and natural history of acute patellar dislocation

BACKGROUND

The goals of this study were to (1) define the epidemiology of acute patellar dislocation, (2) determine the risk of subsequent patellar instability episodes (subluxation and/or redislocation) during the study period, and (3) identify risk factors for subsequent instability episodes.

STUDY DESIGN

Prospective cohort study.

METHODS

The authors prospectively followed 189 patients for a period of 2 to 5 years. Historical data, injury mechanisms, and physical and radiographic measurements were recorded to identify potential risk factors for poor outcomes.

RESULTS

Risk was highest among females 10 to 17 years old. Patients presenting with a prior history of instability were more likely to be female (P < .05) and were older than first-time dislocation patients (P < .05). Fewer first-time dislocators (17%) had episodes of instability during follow-up than patients with a previous history of instability (49%) (P < .01). After adjusting for demographics, patients with a prior history had 7 times higher odds of subsequent instability episodes during follow-up than first time dislocators (adjusted odds ratio = 6.6, P < .001).

CONCLUSIONS

Patellar dislocators who present with a history of patellofemoral instability are more likely to be female, are older, and have greater risk of subsequent patellar instability episodes than first-time patellar dislocators. Risk of recurrent patellar instability episodes in either knee is much higher in this group than in first-time dislocators.

Techniques of medial retinacular repair and reconstruction

Insufficiency of the passive patellar restraints results in lateral patellar instability by allowing excessive lateral displacement of the patella. Although the surgical approach to patellar instability traditionally has been to realign the dynamic elements (muscle forces) that pull the patella laterally, newer techniques have sought to restore the integrity of key medial passive (ligamentous) stabilizers. An increasing body of evidence indicates that the chief medial ligamentous restraint is the medial patellofemoral ligament. The current authors examine the principles of medial retinacular repair and reconstruction as they relate to patellar stability. Individual techniques and approaches are discussed, including primary repair with or without augmentation, and reconstruction using autogenous tendon, allografts, and synthetic graft materials. These procedures share the common objective of addressing the essential lesion in lateral patellar instability to restore the normal passive restraints against lateral patellar displacement.

Current concepts of lateral patella dislocation

Surgical treatment of patellar dislocations, acute and chronic, has evolved significantly over the past decade with the advance of biomechanical knowledge of patellofemoral restraints and injury patterns identified by physical examination and improved imaging techniques. There continues to be no consensus on treatment parameters. Despite the presence of predisposing factors, such as dysplasia or generalized hyperlaxity, medial retinacular injury associated with primary (first-time) patellar dislocations represents a ligament injury, which may result in residual laxity of the injured structure. This residual laxity is defined objectively by an increase in passive lateral excursion of the patella. Repair or reconstructive procedures to restore this medial constraint is considered paramount in any procedure to stabilize the patella against subsequent dislocations. How best to accomplish this continues to be a matter of debate. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is the procedure of choice for stabilizing a kneecap after first-time dislocation, largely because the literature to date does not provide clear guidelines about when more extensive surgery is indicated. Whether or not all first-time dislocators have improved outcome after surgical repair remains speculative, however. Improved outcome would involve both the elimination of recurrent instability episodes and continued satisfactory function of this patella in activities-of-daily-living and sporting activities. These outcomes have not been studied critically in operative versus nonoperative treatment of first-time patellar dislocation. For the first-time dislocator, most investigators would agree that an arthroscopy should be performed if intra-articular chondral damage is suspected. Nonoperative management of first-time patellar dislocations continues to be the preferred practice pattern in the United States. If surgical management is elected, because of individual characteristics of the injury pattern or the patient's lifestyle, it is important to inspect the MPFL along its length and repair any or all ligamentous disruptions. If the ligament is avulsed from the medial epicondyle, reattachment to bone is necessary to restore passive restraint to lateral patella motion. MRI may be useful in order to identify the location and degree of medial soft tissue injury preoperatively. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is a necessary component of all surgical procedures performed to correct objective lateral instability of the patella. The addition of a LRR should be additive to this procedure only when it facilitates other procedures to recenter the patella or when objective lateral tilt by physical examination measurements is present. A practical approach to surgery after patellar dislocation is the minimal amount of surgery necessary to re-establish objective constraints of the patella. Correcting dysplastic factors, in particular tibial tubercle transfers and trochleoplasties, are best reserved if more minimal surgery has failed. This failure is defined as continued functional instability of the kneecap.

Diagnosis and treatment of patients with patellofemoral pain

The patient-athlete with patellofemoral pain requires precise physical examination based on a thorough history. The nature of injury and specific physical findings, including detailed examination of the retinacular structure around the patella, will most accurately pinpoint the specific source of anterior knee pain or instability. Radiographs should include a standard 30 degrees to 45 degrees axial view of the patellae and a precise lateral radiograph. Nonoperative treatment is effective in most patients. Prone quadriceps muscle stretches, balanced strengthening, proprioceptive training, hip external rotator strengthening, patellar taping, orthotic devices, and effective bracing will help most patients avoid surgery. When surgery becomes necessary, indications must be specific. Lateral release is appropriate for patella tilt (abnormal rotation). Painful scar or retinaculum, neuromas, and pathologic plicae may require resection. Proximal patellar realignment may be accomplished using arthroscopic or a combined arthroscopic/mini-open approach. Symptomatic articular lesions and more profound malalignments may require medial or anteromedial tibial tubercle transfer. Clinicians should be particularly alert for symptoms of medial subluxation in postoperative patients and should use the provocative medial subluxation test followed by lateral displacement patellar bracing to confirm a diagnosis of medial patellar subluxation. This problem may be corrected in most patients using a lateral patellar tenodesis. Current thinking emphasizes precise diagnosis, rehabilitation involving the entire kinetic chain, restoration of patella homeostasis, minimal surgical intervention, and precise indications for more definitive corrective surgery.

Results of medial patellofemoral ligament reconstruction in the treatment of patellar dislocation

PURPOSE: The purpose of this study is to describe the technique of medial patellofemoral ligament reconstruction using autogenous hamstrings or autogenous fascia lata and report the results at a minimum 2-year follow-up. Type of Study: This study represents a case series. Patients with patellofemoral instability following patellar dislocation were restrospectively reviewed after being treated with medial patellofemoral ligament reconstruction. No concurrent control group was used. METHODS: Nineteen consecutive patients underwent medial patellofemoral repair or reconstruction in the treatment of patellar instability after patellar dislocation. The reconstructions were performed using autogenous gracilis and/or semitendinosus tendons or a strip of autogenous fascia lata. Fifteen patients were available for interview, examination, and radiographic evaluation, with a mean follow-up of 31.5 months. RESULTS: Subjectively, 10 knees had excellent results, 3 knees obtained good results, 1 knee had a fair result, and 1 knee had a poor result, for a total of 93% improvement overall. Using Fulkerson's functional knee score, 93% had good or excellent results. The average postoperative result on Kujala's score for anterior knee symptoms was 88 (range, 80-100). The Tegner activity level averaged 6.8 preinjury and 6.7 postoperatively. Radiographic evaluation showed significant improvements in the congruence angle by an average of 20 degrees (P =.0006), and in the lateral patellofemoral angle by an average of 10 degrees (P =.0003). CONCLUSIONS: Surgical reconstruction or repair of the medial patellofemoral ligament provides favorable results for the treatment of recurrent patellofemoral dislocations with regard to radiographic findings, patient satisfaction, and functional outcome.