Minimally invasive medial patellofemoral ligament reconstruction for patellar instability using an artificial ligament: A two year follow-up☆,☆☆
Introduction
Acute patellar dislocation frequently leads to recurrence. A systematic review of trials of reconstruction techniques versus conservative rehabilitation reported the rate of re-dislocation after a conservatively managed primary patellar dislocation ranged from 19–54% (5 trials, 339 patients) [1]. This risk is higher in patients with ligamentous laxity, with one retrospective single centre series of 104 individuals treated for patellar dislocation reporting an overall recurrence after an acute dislocation of 30%, and 75% in the subgroup (n = 66) who had ligamentous laxity and abnormal patella position [2].
Various surgical methods have been described in the literature to treat lateral patellar dislocation [3], [4], [5], [6], [7], [8]. Surgical procedures used in Europe have been founded on strict radiographic guidelines, that is, “Le Menu A La Carte”, where all the instability factors are individually corrected [9]. However, the importance of correcting each of these instability factors, alone or in combination is uncertain [9]. There is also uncertainty about the safety and effectiveness of current standard procedures. The above mentioned systematic review comparing surgical repair with conservative rehabilitation in a total of 339 patients with dislocation found no robust evidence of improved clinical (pain, range of motion) or functional (Kujala scores) outcomes in individuals managed with surgical repair [1]. Apart from recurrent dislocation, common post-operative complications reported in the literature are persistent patellofemoral instability, patellofemoral osteoarthritis, loss of flexion, medial subluxation, stiffness and chronic knee pain [1], [3], [7], [8], [10].
The importance of the medial patellofemoral ligament (MPFL) was first described in the late 1950s [11]. A cadaveric study on 25 specimens determined that, biomechanically the MPFL provides 53% of the lateral stabilizing force [12]. It is consequently the most important medial soft-tissue restraint and has been shown to be consistently injured after a patellar dislocation [4]. Brückner was the first to present a technique of transferring the medial part of the patellar ligament to the medial epicondyle to stabilize the patella [13]. But only recently with the evolution of shoulder surgery there has been an increased focus on reconstruction of the MPFL. Several techniques have been described to reduce the high incidence of recurrent dislocation with encouraging clinical results [8].
Numerous sources have been used to reconstruct the MPFL including semitendinosus, semimembranosus, gracilis, quadriceps, vastus medialis retinaculum, or artificial tendons [3], [8], [14], [15], [16]. In 1992, Ellera was the first to describe MPFL reconstruction with an artificial polyester ligament in 30 patients fixed by tunnel fixation on the patella and sub-fascially to the medial femoral condyle [17]. At a minimum of 24 month follow-up, 25 (83%) patients showed improvement with a Crosby and Insall grade of good-excellent [17]. The use of synthetic material is appealing to avoid the morbidity associated with other allograft choices [16]. However, there have been very few other articles describing techniques using synthetic allografts. Nomura et al. in 2000 have recently reported a five year follow-up study of 27 patients treated with MPFL reconstruction with an artificial polyester ligament with staple fixation at the femoral condyle, with 26 (96%) reporting good to excellent outcomes using the Crosby and Insall grading system [5]. But other cohort studies reporting on the use of the artificial ligament question its safety in view of late graft failure, risk of late infection, stiffness, inflammation and cost effectiveness subsequent to use of synthetic allografts [15], [16].
The purpose of our study is:
- 1.
To describe a minimally invasive arthroscopically assisted technique to reconstruct the MPFL using a synthetic allograft.
- 2.
To describe our post-operative rehabilitation protocol.
- 3.
To present data on safety and benefits of the surgical procedure in patellar instability especially in patients with predisposing factors.
Section snippets
Study design & setting
We retrospectively reviewed all individuals who underwent a MPFL reconstruction using an artificial ligament (LARS Ligament, CORIN Ltd, Mersilene Tape MT, or AchilloCordPLUS Ligament, Neoligaments Ltd) for patellar instability by a single surgeon between 2009 and 2012 who had completed 24-month follow-up. Each case was treated at a specialized orthopaedic knee clinic run by the investigators. The University Human Research Ethics Committee and hospitals where the study was conducted approved the
Participants
Our study reviewed 29 individuals (31 knees) with a median follow-up of 43 months (24–68 months). Patient characteristics and baseline clinical findings are summarised in Table 3. The mean patient age at the time of the procedure was 25 (9–44) years. The average duration of instability before the procedure was 1 (0.25–10) year. More than 50% of the study population had an element of generalized ligamentous laxity. 52% of the individuals had Grade IV Instability (Table 4). The age of onset of
Discussion
Over the last two decades, the MPFL has been accepted as the primary restraint amongst the structures stabilizing the patella from cadaveric and biomechanical studies [24], [26]. Our study makes an important contribution to the evidence about the safety and effectiveness of a minimally invasive technique to reconstruct the MPFL using an artificial ligament. We report on the surgical and rehabilitation protocol and provide descriptive information about the clinical benefits and safety in a broad
Conclusion
These mid-term results demonstrate the clinical and functional benefits of this minimally invasive surgical technique using an artificial ligament, and suggest these benefits are achieved with a low risk of complications, with a minimal damage to the extensor mechanism, including in those with severe instability.
Conflict of interest statement
None.
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Cited by (13)
Reconstruction of the medial patellofemoral ligament with nonresorbable suture tape normalizes patellar maltracking independent of patella-side fixation technique
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2023, Knee Surgery, Sports Traumatology, Arthroscopy
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Ethical review committee statement: 014171S Ethical Reference Number University of Notre Dame, Australia (Letter Separate).
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Statement of location: The study was undertaken at Associate Professors M. Al Muderis's clinics, situated at Norwest Private Hospital.