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. Cite this article: Bone Joint J 2013;95-B:900–5

Hypermobility is an acknowledged risk factor for patellar instability. In this case control study the influence of hypermobility on clinical outcome following medial patellofemoral ligament (MPFL) reconstruction for patellar instability was studied. A total of 25 patients with hypermobility as determined by the Beighton criteria were assessed and compared with a control group of 50 patients who were matched for age, gender, indication for surgery and degree of trochlear dysplasia. The patients with hypermobility had a Beighton Score of ≥ 6; the control patients had a score of < 4. All patients underwent MPFL reconstruction performed using semitendinosus autograft and a standardised arthroscopically controlled technique. The mean age of the patients was 25 years (17 to 49) and the mean follow-up was 15 months (6 to 30). Patients with hypermobility had a significant improvement in function following surgery, with reasonable rates of satisfaction, perceived improvement, willingness to repeat and likelihood of recommendation. Functional improvements were significantly less than in control patients (p < 0.01). Joint hypermobility is not a contraindication to MPFL reconstruction although caution is recommended in managing the expectations of patients with hypermobility before consideration of surgery

We report a prospective analysis of clinical outcome in patients treated with medial patellofemoral ligament (MPFL) reconstruction using an autologous semitendinosus graft. The technique includes superolateral portal arthroscopic assessment before and after graft placement to ensure correct graft tension and patellar tracking before fixation. Between October 2005 and October 2010, a total of 201 consecutive patients underwent 219 procedures. Follow-up is presented for 211 procedures in 193 patients with a mean age of 26 years (16 to 49), and mean follow-up of 16 months (6 to 42). Indications were atraumatic recurrent patellar dislocation in 141 patients, traumatic recurrent dislocation in 50, pain with subluxation in 14 and a single dislocation with persistent instability in six. There have been no recurrent dislocations/subluxations. There was a statistically significant improvement between available pre- and post-operative outcome scores for 193 patients (all p < 0.001). Female patients with a history of atraumatic recurrent dislocation and all patients with history of previous surgery had a significantly worse outcome (all p < 0.05). The indication for surgery, degree of dysplasia, associated patella alta, time from primary dislocation to surgery and evidence of associated cartilage damage at operation did not result in any significant difference in outcome.

This series adds considerably to existing evidence that MPFL reconstruction is an effective surgical procedure for selected patients with patellofemoral instability.

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The Oswestry-Bristol Classification (OBC) was recently described as an MRI-based classification tool for the femoral trochlear. The authors demonstrated better inter- and intraobserver agreement compared to the Dejour classification. As the OBC could potentially provide a very useful MRI-based grading system for trochlear dysplasia, it was the aim to determine the inter- and intraobserver reliability of the classification system from the perspective of the non-founder.

The tensile strength of the medial patellofemoral ligament (MPFL), and of surgical procedures which reconstitute it, are unknown. Ten fresh cadaver knees were prepared by isolating the patella, leaving only the MPFL as its attachment to the medial femoral condyle. The MPFL was either repaired by using a Kessler suture or reconstructed using either bone anchors or one of two tendon grafting techniques. The tensile strength and the displacement to peak force of the MPFL were then measured using an Instron materials-testing machine. The MPFL was found to have a mean tensile strength of 208 N (SD 90) at 26 mm (SD 7) of displacement. The strengths of the other techniques were: sutures alone, 37 N (SD 27); bone anchors plus sutures, 142 N (SD 39); blind-tunnel tendon graft, 126 N (SD 21); and through-tunnel tendon graft, 195 N (SD 66). The last was not significantly weaker than the MPFL itself

Introduction. As intra-operative fluoroscopic identification of the isometric MPFL attachment to the femur can be imprecise and laborious in a surgical setting, we used clinical criteria to identify the isometric point and then studied post-operative radiographs to find out whether it was achieved and compared it with functional outcome. Materials and Methods. Sixteen patients underwent 17 MPFL reconstructions using autologous semi-tendinosis tendon graft. Clinical judgement was used to identify the optimal point for femoral attachment of the MPFL without fluoroscopy control. Post-operative radiographs at 2 weeks were analysed to confirm whether an isometric point for the reconstructed MPFL was achieved by dividing the distal femur into 4 quadrants by 2 lines on the lateral radiograph. Telephonic interview was conducted to assess functional scores using the Kujala score at a mean follow-up of 13 months. Results. In only 4 of the 17 cases, the femoral point of attachment lay in the radiographically isometric (antero-proximal) quadrant. In 8 of 17 knees, the point of MPFL attachment lay in the antero-distal quadrant. However, there was an improvement in the functional score in 14 of 16 patients, with none reporting recurrence of patellar instability. The position of the reconstructed MPFL did not correlate with functional score. Conclusion. Over-reliance on a clinical method alone for identification of the optimal point for MPFL attachment without an intra-operative radiograph leads to radiographically non-isometric positioning in a majority of cases. In the clinical setting, however, this does not correlate with adverse functional outcome, although intra-operative fluoroscopy may improve the anatomical isometry, and we therefore suggest the use of a qualitative clinical method to achieve optimal

Abstract. Patellofemoral Arthroplasty (PFA) is an alternative to TKA for patellofemoral osteoarthritis that preserves tibiofemoral compartments. It is unknown how implant positioning affects biomechanics, especially regarding the patella. This study analysed biomechanical effects of femoral and patellar component position, hypothesising femoral positioning is more important. Nine cadaveric knees were studied using a repeated-measures protocol. Knees were tested intact, then after PFA implanted in various positions: neutral (as-planned), patellar over/understuffing (±2mm), patellar tilt, patellar flexion, femoral rotation, and femoral tilt (all ±6°). Arthroplasties were implemented with CT-designed patient-specific instrumentation. Anterior femoral cuts referenced Whiteside's line and all femoral positions ensured smooth condyle-to-component transition. Knee extension moments, medial patellofemoral ligament (MPFL) length-change, and tibiofemoral and patellofemoral kinematics were measured under physiological muscle loading. Data were analysed with one-dimensional statistical parametric mapping (Bonferroni-Holm corrected). PFA changed knee function, altering extension moments (p<0.001) and patellofemoral kinematics (p<0.05), but not tibiofemoral kinematics. Patellar component positioning affected patellofemoral kinematics: over/understuffing influenced patellar anterior translation and the patellar tendon moment arm (p<0.001). Medially tilted patellar cuts produced lateral patellar tilt (p<0.001) and vice versa. A similar inverse effect occurred with extended/flexed patellar cuts, causing patellar flexion and extension (p<0.001), respectively. Of all variants, only extending the patellar cut produced near-native extension moments throughout. Conversely, the only femoral effect was MPFL length change between medially/laterally rotated components. PFA can restore native knee biomechanics. Provided anterior femoral cuts are controlled and smooth condyle-to-component transition assured, patellar position affects biomechanics more than femoral, contradicting the hypothesis

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis. Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis. This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients. Cite this article: Bone Joint J 2017;99-B:159–70

Aim. This study looks for correlation between pre-operative MRI and intra-operative surgical findings regarding the site of medial patellofemoral ligament (MPFL) rupture in first time patella dislocaters with the aim of confirming the reliability of this modality of imaging. Methods. A retrospective analysis of all patients who were referred for MRI following patella dislocation was performed. The surgical and MRI findings of those who subsequently underwent MPFL repair were compared to look for any correlation. Results. 41 patients were first time patella dislocators and 38 had MPFL rupture diagnosed on MRI. Of these 19 progressed to surgical intervention and 17 had adequate data available from the notes to permit comparison. All of the MPFLs ruptured at the patella insertion. In 76.5% (13/17) of patients the site of MPFL rupture was correctly identified on MRI scan. Of those that were discordant, 3/4 had the site of rupture identified as the femoral insertion on MRI and on 1/4 had an MRI suggestive of rupture at both the femoral and patella insertions. Conclusion. MPFL rupture is common in first time dislocations occurring in 93% of this cohort on MRI. There was a predominance for patella insertion rupture in our study which contrasts with the majority of the published literature. By correlating surgical and radiological findings we can conclude that while MRI can accurately diagnose MPFL rupture at the patella insertion it is less accurate in identifying rupture at the femoral insertion

AIMS. The aim of this study was to assess the knee function after MPFL reconstruction with single hamstring autograft. METHODS-RESULTS. In this case series 68 patients (69 knees) were treated in total. Clinical and radiological evidence of patellar instability and MPFL rupture or deficiency was documented prior to surgery. The MPFL was reconstructed with semitendinosus autograft. The free end of the graft was rerouted through the most distal part of the medial intermuscular septum proximally to the adductor tubercle, to the superomedial border of the patella, where it was fixed, whereas its distal insertion to the tibia was preserved. Knee function was assessed preoperatively and postoperatively with the use of Kujala, Tegner, Lysholm and International Knee Documentation Committee (IKDC) scores. There were 46 male and 22 female patients with an average age of 25.8 years (median age 23) ranging from 11 to 54 years. The mean follow-up was 19.6 months (range 6-54 months). Ten of the patients had findings of femoral trochlear dysplasia. All knee functional scores significantly improved postoperatively. Kujala score improved from 56 to 84, Tegner score improved from 2 to 6, IKDC score improved from 48 to 75 and Lysholm score improved from 53 to 80. One of the patients required revision of the MPFL reconstruction following traumatic redislocation of the patella. CONCLUSIONS. Rerouting of the semitendinosus tendon for the reconstruction of the MPFL is an effective method for the treatment of patellofemoral instability with very good to excellent functional results

Purpose. Investigate the functional outcome of medial patellofemoral ligament (MPFL) surgery for patella instability. Compare functional outcome of direct MPFL repair and reconstruction using hamstring graft. Methods. All patients that underwent MPFL surgery for patella instability between 2007-2010 were retrospectively identified from operative records. Patients were divided based on whether they underwent direct repair of MPFL, or reconstruction using hamstring graft. The Kujala scoring questionnaire for patellofemoral disorders (max score 100) was used to assess their functional outcome following surgery. Results. 33 patients were identified, 11 were not suitable for inclusion in the study. The remaining 22 patients had a total of 25 operations for patella stabilisation (3 bilateral). Average age of patient at time of surgery was 21 (15-33), 15 male and 7 female. 17 had direct repair of MPFL, 8 had reconstruction using hamstring graft. Of the 8 reconstructions 6 were primary procedures and 2 were for failed direct repair due to further traumatic injury. Mean follow-up period was 17 months (6-43). Mean Kujala score overall 91.6, mean score for reconstruction group 93.2, direct repair score 90.7. Total number of further patella dislocations in the repair group was 1/17 (5.9%). No patients in the reconstruction group reported any further patella dislocations following their surgery. Conclusion. Both direct repair and reconstruction of MPFL for patella instability demonstrate high functional outcome at short/mid-term follow up. Our high success rate in direct MPFL repair, good functional outcome and low re-dislocation rate is better than that quoted in the current literature

Aims

The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process.

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The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach.

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Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure.

Purpose. To assess the midterm functional results after Medial Patellofemoral Ligament (MPFL) reconstruction with single semitendinosis autograft in patients with patellofemoral instability. Methods - Results. Forty six knees (45 patients) with patellofemoral instability were treated with surgical stabilisation of the patella with a single semitendinosis autograft and followed up for a minimum of 24 months. The average follow-up was 33.5 months (range 24-54 months). Clinical evidence of patellar instability and radiological (MRI) evidence of MPFL rupture or deficiency was documented prior to surgery. The average post injury interval was 22.3 months. Ipsilateral joint co-morbidities included previous lateral release or distal realignment (n=10), patellofemoral joint (PFJ) dysplasia (n=14) and concurrent ACL, PCL and/or MCL rupture (n=6). Knee function was assessed preoperatively and postoperatively with the use of Kujala, Tegner, Lysholm and International Knee Documentation Committee (IKDC) scores. There were 34 male and 11 female patients with a mean age of 32.5 years (range 17 - 60 years). All measured knee function scores improved postoperatively. Kujala score improved from 58 to 77 (95%CI +/− 9.71). Tegner score improved from 3 to 5 (95%CI+/− 0.65). IKDC score improved from 51 to 75 (95%CI +/− 5.27) and Lysholm score improved from 59 to 79 (95%CI +/− 6.5). Conclusions. MPFL reconstruction with semitendinosis autograft is an effective treatment at a minimum of 24 months (midterm) follow-up in patients with patellofemoral instability even in the presence of heterogeneous knee co-morbidities such as PFJ dysplasia, previous lateral release and failed realignment surgery

Introduction. There are numerous surgical techniques for medial patellofemoral ligament (MPFL) reconstruction. Problems with certain techniques include patellar fracture and re-rupture. Aim. To investigate the functional outcomes of MPFL reconstructions performed using a free gracillis tendon graft, oblique medial patella tunnel and interference screw femoral fixation. Patients were selected for MPFL reconstruction if they had recurrent patellar dislocations, and with the use of clinical and radiographic evaluation. Methods. A prospective case series of 31 consecutive knees in 28 patients underwent reconstruction of the MPFL using a free gracillis tendon graft, oblique medial patella tunnel and interference screw femoral fixation. Our primary outcome measure was the Kujala patellofemoral questionnaire. This was assessed preoperatively and postoperatively at 6 weeks and 3, 6, 9, 12, 18, 24 months and at final follow up. Secondary outcome measures included Fulkerson patellofemoral scores at the same time intervals, return to work, return to preoperative sport and complications. Results. The median follow up time was 25 months (range 12 – 44 months). Kujala scores improved from 58 to 93 (p < 0.002) and Fulkerson scores improved from 58 to 95 (p < 0.002) pre- and postoperatively respectively. The median return to work was 8 weeks and return to preoperative sport was 11 weeks. There were 2 revisions as a result of trauma. There were no instances of patellar fracture in this case series. Conclusions. MPFL reconstruction using a free gracillis tendon graft, oblique medial patella tunnel and interference screw femoral fixation appears to be an effective surgical intervention for patellar instability. This technique also reduces the risk of patellar fracture, a common shortcoming with many other techniques

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Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics.

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The Oswestry-Bristol Classification (OBC) is an MRI-specific assessment tool to grade trochlear dysplasia. The aim of this study is to validate clinically the OBC by demonstrating its use in selecting treatments that are safe and effective.

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Trochlear dysplasia is a significant risk factor for patellofemoral instability. The Dejour classification is currently considered the standard for classifying trochlear dysplasia, but numerous studies have reported poor reliability on both plain radiography and MRI. The severity of trochlear dysplasia is important to establish in order to guide surgical management. We have developed an MRI-specific classification system to assess the severity of trochlear dysplasia, the Oswestry-Bristol Classification (OBC). This is a four-part classification system comprising normal, mild, moderate, and severe to represent a normal, shallow, flat, and convex trochlear, respectively. The purpose of this study was to assess the inter- and intraobserver reliability of the OBC and compare it with that of the Dejour classification.

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The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia.