Patellar Instability: Principals of Soft Tissue Repair and Reconstruction

Simple Cost-Effective Reinsertion of Avulsed Medial Patellofemoral Ligament in Acute Patellar Dislocation

The medial patellofemoral ligament (MPFL) is the main restraining force against lateral patellar displacement in the first 20° of flexion and is disrupted after patellar subluxation or dislocation. Management of acute patellar dislocations is controversial, and many clinicians opt for conservative treatment in the acute phase. However, a traumatic rupture of the MPFL warrants surgical attention. Several considerations must be made by surgeons attempting reinsertion of the MPFL, including the choice of implant and timing of surgery, to restore the anatomy and biomechanics of the patellofemoral joint. Our aim is to achieve robust reinsertion of the MPFL restoring the anatomy and biomechanics of the patellofemoral joint using a simple, reproducible, and economical technique. We present MPFL reinsertion to the medial border of the patella in an acute patellar dislocation with a braided No. 2 ultrahigh-molecular-weight polyethylene suture (No. 2 Ultrabraid; Smith & Nephew, Memphis, TN) that is passed through 3 transverse parallel tunnels and tied over a bone bridge on the lateral border of the patella. This technique is simple with no implanted hardware, does not have the risk of donor-site morbidity of MPFL reconstruction, and can be performed in skeletally immature patients without growth plate concerns.

Estudo biomecânico de diferentes dispositivos de fixação femoral na reconstrução do ligamento patelofemoral medial em joelhos de suínos

Objetivo Avaliar diferentes dispositivos de fixação femoral na reconstrução do ligamento patelofemoral medial para comparar sua eficácia quanto à força de fixação até a falha em joelhos suínos.

Métodos Foram ensaiados 30 joelhos de suínos subdivididos em 3 grupos de 10 joelhos. Os enxertos retirados foram dissecados de tendões extensores das patas dos suínos. Cada grupo teve o enxerto fixado ao fêmur com parafuso de interferência, âncora, ou tenodese no tendão adutor. Os 3 métodos foram submetidos à testes biomecânicos utilizando uma máquina universal de ensaio de tração com uma velocidade de 20 mm/min.

Resultados Verificamos que a média mais elevada da resistência linear sob tração lateral (185,45 ± 41,22 N) ocorreu no grupo 1: “fixação por parafuso,” seguido do grupo 2: “fixação por âncora” (152,97 ± 49,43 N), e a média foi menor no grupo 3: “fixação por tenodese” (76,69 ± 18,90 N). Para a margem de erro fixada (5%), comprovou-se a diferença significativa entre os grupos (p < 0,001) e também através dos testes de comparações múltiplas (entre os pares de grupos) verificou-se a ocorrência de diferenças significativas. A variabilidade expressada por meio do coeficiente de variação mostrou-se reduzida, já que a referida medida foi inferior a 33,3%.

Conclusão O uso de parafusos de interferência no túnel ósseo de joelhos porcinos é suficientemente forte para fixação femoral na reconstrução do ligamento patelofemoral medial, assim como a fixação com âncoras montáveis com fio de alta resistência. Entretanto, a tenodese no tendão adutor mostrou-se frágil para essa finalidade.

Effective patellofemoral joint stabilization and low complication rates using a hardware-free MPFL reconstruction technique with an intra-operative adjustment of the graft tension

PURPOSE

Even if medial patellofemoral ligament (MPFL) reconstruction is a proven method, complications such as implant loosening, patella fractures, recurrent luxations, knee pain or knee stiffness are frequently described. Besides a correct tunnel positioning and implant-specific complications, this might be caused by difficulties with an appropriate graft tensioning. The study presented here is a necessary first step in exploring our technique of a double-limbed, hardware-free MPFL reconstruction, which provides another way to test and adjust the graft tension before permanent fastening.

METHODS

Thirty consecutive patients (m/f = 18/12) with recurrent dislocations were evaluated after a mean follow-up of 24 months. Patients who had additional procedures such as a trochleoplasties, tibial tubercle transfers and derotational osteotomies were not included. Besides a standardized clinical examination, different scorings and possible complications were evaluated.

RESULTS

The mean Kujala score improved significantly from 57 ± 15 to 92 ± 10. The Lysholm and IKDC score increased significantly from 59 ± 11 to 95 ± 6 and from 49 ± 9 to 89 ± 9, respectively. No patient reported a re-dislocation, subluxation or showed a positive apprehension. A total of 23 patients were engaged in regular physical activities. All but one, who lost interest, returned to the same sports. Because some did not follow our recommendation to return to sports after a rehab of at least 10-12 weeks, the period for a return was relatively short (median of 12 weeks, range 3-25 weeks). Four patients reported a moderate anterior knee pain only occurring after increased loads such as longer runs or workouts. One of these showed a slight flexion deficit of less than 20°. A severe motion deficit or stiffness was not noticed.

CONCLUSIONS

Even if a larger, clinical outcome study is needed to ensure the efficacy and safety of our method, it seems to provide a good clinical outcome, a correspondingly high satisfaction and a low incidence of complications. The possibility to adjust graft tension might help in minimizing complications caused by difficulties with an appropriate graft tension.

LEVEL OF EVIDENCE

IV.

Medial patellofemoral ligament reconstruction using a bone groove and a suture anchor at patellar: a safe and firm fixation technique and 3-year follow-up study

Background

Graft fixation is critical to the restoration of the medial patella of femoral ligament function and long-term success. Numerous fixations at the patella have been described, while the complications including patellar fractures, violation of the posterior patella and delay of tendon-to-bone healing remain significant challenges. Here, we describe a safe and firm fixation at the patellar for medial patellofemoral ligament (MPFL) reconstruction and explore the safety angle of drilling the suture anchor at different morphology of the patellar. Moreover, we evaluate the results at a 3-year follow-up.

Methods

Combined bone groove and suture anchor fixation at the patella was performed on 26 patients (16 females, 10 males; mean age 26.3 ± 4.7 years) diagnosed with recurrent patellar dislocation. The drilling direction of the suture anchor referred to the safety angle according to the Wiberg type classification. The safety angle was defined as the angle between the drill tunnel and a line that connected the medial and lateral margins of the patella and was established following computed tomography assessment of 117 patients who were diagnosed with patellar dislocation in our hospital according to the Wiberg type classification (I:29, II:65, III:23). X-ray, Lysholm, Kujala and Tegner scores were obtained preoperatively and at the time of final follow-up.

Results

There were no patellar complications, including fracture and redislocation. Average congruence, patella tilt angles and lateral patella angle were significantly changed (P < 0.01). The Lysholm, Kujala and Tegner scores were significantly increased (P < 0.01). The safe angles of male and female patients according to the patellar Wiberg type classification were less than 45.32 ± 1.76 and 41.20 ± 1.33, 69.74 ± 1.38 and 63.66 ± 1.45 and 84.11 ± 1.67 and 80.26 ± 1.73, respectively.

Conclusions

We achieved encouraging results with this fixation at the patellar. When drilling from Wiberg type I to type III patellar, the suture anchor should be more vertical. When fixing the patellar of female patients, the drilling suture anchor should be more sloping.

A prospective randomized trial evaluating two different tensioning techniques for medial patellofemoral ligament reconstruction

BACKGROUND

In the literature, graft tension was mostly assessed under direct arthroscopy vision for a MPFL reconstruction. The purpose of this study was to prospectively assess the outcomes of MPFL reconstruction with graft tension of self-balance technique in comparison with arthroscopy-view technique.

METHODS

Sixty patients with recurrent patellar dislocation were randomly divided into two groups to undergo MPFL reconstruction with graft tension either by the self-balance technique (SB group) or the arthroscopy-view technique (AV group). At a minimum of 24months of follow up, patellar stability was evaluated with the apprehension test. Patellofemoral morphology was measured on an axial CT scan and knee function was evaluated using the Kujala and Lysholm scores.

RESULTS

Twenty-three patients in the SB group and 25 patients in the AV group were followed for a minimum of 24months. No recurrent dislocation or subluxation was reported. Apprehension signs remained in two patients in the SB group and in one patient in the AV group. The postoperative Kujala score for the SB group and AV group were 91.4±5.1 and 90.3±5.5, respectively, and the Lysholm score was 90.1±6.4 and 88.4±6.3, respectively, with no significant differences. On CT images, congruence angle, patellar tilt angle and lateral patellar angle were restored to the normal range.

CONCLUSIONS

At a minimum of 24months of follow-up, graft tensioning using the self-balance technique yielded similar patellar stability and knee function compared with the arthroscopy-view procedure in the MPFL reconstruction. The self-balance technique as a simple procedure is recommended as a good alternative method for graft tensioning in the MPFL reconstruction.

MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION TO TREAT RECURRENT PATELLAR DISLOCATION

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Biomechanical comparison of patellar fixation techniques in medial patellofemoral ligament reconstruction

BACKGROUND

Multiple techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been described; however, little is known about the biomechanical properties of these techniques. Fixation of the graft to the patella has not been studied in a human cadaveric model.

HYPOTHESIS/PURPOSE

The purpose of this study was to compare the ultimate failure load and stiffness of 2 different MPFL patellar fixation techniques: suture anchor fixation and interference screw fixation. The null hypothesis was that the suture anchor group would show no difference in the ultimate failure load and stiffness compared with the interference screw group.

STUDY DESIGN

Controlled laboratory study.

METHODS

Reconstruction of the MPFL with semitendinosus autografts was performed in 8 pairs of fresh-frozen cadaveric knees (16 knees total; mean age, 55.8±7.7 years). The specimens were randomly assigned to 2 groups of 8 specimens each based on the method used to fix the graft to the medial patella: suture anchor or interference screw fixation. Each reconstruction technique was performed on 1 knee from the same cadaveric specimen. Suture anchor reconstruction was completed with 2 parallel 3.0-mm biocomposite suture anchors. Interference screw fixation was accomplished with two 4.75-mm biocomposite interference screws docked in parallel tunnels. The reconstructions were cyclically loaded for 10 cycles to 30 N and then tested to failure at a constant displacement rate of 6 mm/s with a line of pull parallel to the anchors or interference screws. Ultimate failure load (N), stiffness (N/mm), and mode of failure were recorded for each specimen.

RESULTS

The suture anchor group had a significantly lower mean failure load (201.54±63.14 N) than the interference screw group (299.25±99.87 N) (P=.007). The suture anchor group also had significantly lower mean stiffness (20.60±6.78 N/mm) compared with the interference screw group (34.66±10.74 N/mm) (P=.007). The most common mode of failure in the suture anchor group was failure at the graft-suture interface. In the interference screw group, the most common mode of failure was the tendon graft pulling out of the tunnel.

CONCLUSION

Interference screw fixation to the medial patella was found to be significantly stronger than suture anchor fixation when comparing the ultimate failure load and stiffness.

CLINICAL RELEVANCE

This study compares the biomechanical properties of 2 commonly used methods for patellar graft fixation in MPFL reconstruction surgery. It supports the use of interference screw fixation based on the ultimate load and stiffness, although suture anchor fixation may be sufficient when compared with the native MPFL based on previously published data.

A simple technique for reconstruction of medial patellofemoral ligament with bone-fascia tunnel fixation at the medial margin of the patella: a 6-year-minimum follow-up study

Background

Medial patellofemoral ligament (MPFL) reconstruction has become an accepted technique to treat patellofemoral instability, and numerous surgical techniques have been described to reconstruct the MPFL. We describe a MPFL reconstruction procedure where bone-fascia tunnel fixation occurs at the medial margin of the patella for recurrent patellar dislocation.

Objective

MPFL reconstruction is the preferred operative treatment for recurrent patellar dislocation. The purpose of this study was to report a simple technique for reconstruction of medial patellofemoral ligament with bone-fascia tunnel fixation at the medial margin of the patella for recurrent patellar dislocation and to evaluate the results at 6-year-minimum follow-up.

Methods

The study included 65 patients (28 males, 37 females; mean age, 29.4 ± 5.6 years) who underwent MPFL reconstruction using the bone-fascia tunnel fixation at the medial margin of the patella technique and who were followed for a mean duration of 78.5 ± 3.8 months. Objective assessment, Kujala scale, Lysholm score, and Tegner activity score were obtained preoperatively and at the time of final follow-up.

Results

There were no patellar complications, including redislocation, in the present study. The congruence angle had significant improvement from 19.2° ± 6.3° before surgery to −6.03° ± 0.50° at the last follow-up. The lateral patellar angle had significant improvement from −6.9° ± 3.5° before surgery to 5.1° ± 2.4° at the last follow-up. The patellar tilt angle had significant improvement from 24.5° ± 5.2° before surgery to 12.30° ± 1.90° at the last follow-up. The Kujala score was significantly increased from 52.9 ± 3.2 points preoperatively to 90.1 ± 5.8 points postoperatively (P < 0.05). The mean Lysholm score was significantly increased from 47.2 ± 5.2 to 92.5 ± 6.2 points postoperatively (P < 0.05). The Tegner activity score improved overall from 3.1 ± 0.6 points to 5.8 ± 0.9 points at follow-up.

Conclusion

We have done a simple technique where the MPFL is reconstructed safely to avoid patella fracture, anatomically to restore physiological kinematics and stability, and economically to reduce costs with bone-fascia tunnel fixation at the medial margin of the patella.

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.

Aperture fixation instead of transverse tunnels at the patella for medial patellofemoral ligament reconstruction

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction is an effective option for the treatment of recurrent patellar instability. Most techniques utilize the passage of a tendon graft through tunnels at the patella with the risk of patellar fracture. The purpose of this study was to investigate the strength of the recent MPFL reconstruction techniques (transverse tunnel, interference screw, anchor, and docking technique).

METHODS

Thirty-six saw bones were divided into four groups (transverse tunnel, interference screw, anchor fixation, and docking technique) with nine patellae in each. Patella-tendon constructs were pre-loaded to 10 N and cyclically loaded for 20 cycles from 2 to 30 N under load control at a rate of 5 N/sec. The construct was then tested to failure at a constant displacement rate of 6 mm/sec. Ultimate load (N), stiffness (N/mm), and failure mode were recorded for each specimen.

RESULTS

The docking group had lower ultimate load [106 (SD 41) N] and stiffness [14 (SD 2) N/mm] values than the other groups tested (P = 0.007). The anchor group had lower stiffness [21 (SD 6) N/mm] values than the tunnel group [28 (SD 3) N/mm (P = 0.01)] and the interference screw group [31 (SD 6) N/mm, (P = 0.004)]. There was no significant difference in the ultimate load between anchor [299 (SD 116) N], tunnel [304 (SD 140) N], and interference screw groups [241 (SD 103) N] (n.s.).

CONCLUSION

Aperture fixation techniques, especially interference screw fixation, were as strong as the technique utilizing tunnels in the patella for MPFL reconstruction.

Hamstring graft fixation in MPFL reconstruction at the patella using a transosseous suture technique

Controversy still exists about fixation methods of a hamstring graft to the patella in case of medial patellofemoral ligament (MPFL) reconstruction. This article presents a surgical technique of hamstring tendon graft fixation to the anatomical MPFL insertion on the patella using transosseous sutures. A superficial bony sulcus is created at the anatomical MPFL insertion site on the medial patellar rim with a bur. A looped hamstring tendon graft is fixed to this superficial sulcus by a pair of nonresorbable transosseous sutures passed across the patella. The retinaculum is sutured on top of the hamstring tendon graft at the level of the patella for additional fixation. The technique avoids bone tunnels as well as hardware at the patella. It reduces the risk of intraoperative or postoperative patella fracture or implant-related complications. The stable transosseous fixation technique allows for early rehabilitation.

Management of overtight medial patellofemoral ligament reconstruction

The clinical presentation of an overtight medial patellofemoral ligament (MPFL) reconstruction can differ depending on whether it is too tight in extension (extensor lag) or too tight in flexion (anterior knee pain and loss of flexion). We report one clinical case of each presentation. Both cases were treated with a percutaneous release of the graft. After the release, both patients regained a full active range of motion without residual symptoms. These complications demonstrate that the adjustment of the graft tensioning as well as its femoral position are critical steps in MPFL reconstruction. This procedure requires training and experience in order to avoid early complications related to malposition or inappropriate tensioning of the graft. A surgical management for these overtight reconstructions is recommended, as it will restore function and range of motion, and prevent late patellofemoral 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.

Recurrent patellar dislocation after medial patellofemoral ligament reconstruction

We report on three cases of recurrent lateral patellar dislocation following a medial patellofemoral ligament (MPFL) reconstruction for patellar instability. In all three cases, an isolated MPFL reconstruction was performed with a double autogenous gracilis graft. The patellar fixation was done through bone tunnels. All three patients presented with a definite moderate to severe traumatic episode resulting in a recurrent patella dislocation and a transverse avulsion fracture at the medial rim of the patella. All three were treated by an open reduction and internal fixation with good results. No complication or recurrent dislocations occurred. We suggest that this complication is caused by the original underlying pathology such as dysplastic trochlea, abnormal TT-TG, patella alta and hyperlaxity, resulting a greater reliance upon the reconstructed MPFL for patellar stability. When subjected to a severe stress, the graft, which is stronger and stiffer than the original MPFL, will cause a fracture through the medial edge of the patella. This weak area results from the previous drill holes, which act as stress risers.