Recurrent patella dislocation is a well-recognized complication after primary dislocation of the patellofemoral joint. We propose that acute surgical management of the injury minimizes this risk. Between February 2006 and August 2010 47 patients (49 knees) with a mean age of 17.9 (range 12–31) at the time of surgery who sustained a patellofemoral joint dislocation for the first time were treated with an acute repair of the medial patellofemoral ligament. Patients presenting to our fracture clinic following a primary lateral dislocation of the patella were investigated with an MRI scan and with consent, proceeded to have an examination under anaesthesia and arthroscopy of the injured knee. An easily dislocatable patella in the presence of a confirmed medial patellofemoral ligament rupture was the indication for open repair. All patients treated surgically were followed up for a period of 24–72 months where the primary outcome measure was further dislocation. An evaluation of symptoms, functional recovery, restoration of range of movement and patient satisfaction was made supported by the Lysholm knee score. Our results confirm that acute repair of the medial patella femoral ligament in selected patients reduces the risk of further dislocations and results in a overall good functional outcome and patient satisfaction with minimal complications

Introduction. Patellar stability is an important component for a correct kinematic behaviour of the knee that depends on several factors such as joint geometry, muscles strength and soft tissues actions. Patellofemoral (PF) maltracking can results in many joint disorders which can cause pain and mobility alterations. The medial patellofemoral ligament (MPFL) is an important stabilizing structure for the patellofemoral joint. The aim of this study was to analyze patellofemoral kinematics with particular attention to the contribution of MPFL on patella stability. Methods. Using a navigation system PF kinematics during passive flexion/extension movements with quadriceps loaded at 60N, was recorded on 6 cadavers in three different anatomical conditions: intact knee, MPFL cut and MPFL reconstructed with graft. Test on patella was conducted without lateral force and with applied lateral force (25N). Tilt and lateral shift was evaluated in both cases at 0°. 30°, 60°and 90° of flexion. Results. Test results without applied force showed that there is no statistical difference between intact knee and MPFL cut conditions in all ranges of flexion, both for medio-lateral shift and tilt, which have low values. In test with applied force a significative increase of patellar lateral translation at 30° (16,8 ± 13,4 mm) and 60° (18,6 ± 6,4 mm) was found. MPFL reconstructed knee behaviour was not statistically different to intact knee both for tilt and medio-lateral shift. Therefore lateral translation was widely reduced with the graft. Conclusions. Without applied stress intact knees and MPFL cut knees behave in the same way. In applied load conditions MPFL cut knees show wide lateral translation in respect to intact and reconstructed knees. MPFL reconstructed knees are similar to intact knee therefore MPFL restraint is significant only in stress conditions. This may indicate that the MPFL is a aponeurosis, with an active role under stress, but low role during neutral knee flexion

Patellofemoral instability is common injury and proximal soft tissue stabilisation via MPFL reconstruction or imbrication is the mainstay of treatment. The contribution of certain pathoanatomies to the failure of patellofemoral stabilisation is unknown. The purpose of this study was to analyse the failure rate of patellar stabilisation procedures in a large cohort as measured by re-dislocation of the patella. A secondary purpose was to identify the pathoantomical features that may have predisposed these patients to failure.

Between May 2008 and March 2014, 207 MPFL reconstructions and 70 MPFL imbrications were performed by a single surgeon. Post-operative assessment included clinical examination to assess the integrity of the MPFL graft, plain radiographs and the Banff Patellofemoral Instability Instrument (BPII), a disease-specific outcome measure. Failures were identified and risk factors including trochlear dysplasia, patella alta, generalised ligamentous laxity (GLL), femoral tunnel position and rotational abnormalities were evaluated as contributing factors.

There were 48 male and 178 female patients. The mean duration of follow-up was 24.1 months (SD 9.4, range 12–74). The average age at time of surgery was 24.81 years (SD 8.87, range 50.35–8.99). The average BMI was 23.75 (SD 3.62, range 36.70–14.90). There were 10 failures in the MPFL reconstruction group (4.8%), 1 male and 9 females. Femoral tunnel position was assessed in relation to Schottle's point as good or excellent in all 10 cases. In terms of pathoanotomy, 8/10 failures had high-grade trochlear dysplasia, 1/10 had patella alta, 6/10 had a Beighton score of >/= 4, and 3/10 had clinically significant rotational abnormalities of the lower extremity. The primary cause attributed to the 10 failure cases was trauma in two, trochlear dysplasia in three, rotational abnormalities in one, combined femoral anteversion and GLL in two, and combined trochlear dysplasia and GLL in two. There were 13 failures in the MPFL imbrication group (18.6%), 2 males and 11 females. Among these failures, 4/13 had high-grade trochlear dysplasia, 3/13 had patella alta, 10/13 had a Beighton score of >/= 4, and one had clinically significant rotational abnormalities of the lower extremity. The primary pathology that was considered to contribute to the imbrication failure cases was trochlear dysplasia in four, generalised ligamentous laxity in six, rotational abnormalities in one, patella alta with trochlear dysplasia in one, and generalised ligamentous laxity with trochlear dysplasia in one. Prior to surgical failure the mean BPII score for the failure group was 71.5/100, compared with 74.6/100 for the remainder of the cohort.

MPFL reconstruction is highly successful surgical procedure for stabilising the unstable patella with a failure rate of only 4.8%. Higher failure rates are seen in patients undergoing imbrication of the MPFL compared to a reconstruction. Pathoanatomies that contribute to failure vary between patients with the most common being trochlear dysplasia and generalised ligamentous laxity.

A prospective study was done to assess the outcome of MPFL reconstruction for patellar instability using quadriceps graft. MPFL reconstruction was done using superficial strip of quadriceps by an anteromedial incision and attached close to medial epicondyle of femur. There were 15 knees in thirteen patients with a mean age of 23.4 years. All patients had MPFL reconstruction and 5 had tibial tuberosity transfers. With a mean follow-up of 39.4 (12–57) months, the mean pre-op Kujala scores improved from 47.8 to 87.2. The mean Lysholm scores improved from 54.2 to 86.8. None of the patients had patella re-dislocations. MPFL reconstruction with quadriceps graft appears to be effective producing good results in patients with patellar instability.

Background:. During the past two decades the medial Patellofemoral ligament has come to the fore as the essential lesion of acute patella dislocation and its reconstruction in cases of chronic instability seems logical. The femoral insertion of the medial Patellofemoral ligament (MPFL) is key to the isometry or desired anisometry of the reconstruction. Radiographic landmarks for the femoral insertion has been described in literature most notably by Schottle et al. AJSM 2007. We examined the consistency of these landmarks of the femoral insertion of the MPFL. Methods:. 24 unpaired knees of cadavaric specimen were dissected for the origin of the MPFL. A radiographic marker was then placed in the centre of the femoral attachment of the MPFL and a direct lateral X-ray obtained of the distal femur. The sweet spot was defined according to the landmarks described by Schottle et al and deviation from the sweet spot was measured. Results:. The average distance from the centre of the described radiological centre of the MPFL was 5.4 mm. In six cases the ligament insertion was 5.6 mm distal to the ideal radiological centre. We did not find the origin of the MPFL to be a consistent radiological landmark due to a wide insertion of the ligament on the femur with a variable anisometric centre. We recommend dynamically testing the insertion site of the MPFL around a guide wire inserted into the femur instead of relying solely on the radiological position

Background of study. Medial patellofemoral ligament (MPFL) reconstructions are often performed using gracilis autografts, this can be associated with donor site morbidity and complications. The use of synthetic material can circumvent a harvest operation and have previously been demonstrated to be effective in other types of reconstructive procedures and may be effective in MPFL reconstruction. We report our experience and clinical results with the use of FiberTape (FT) in MPFL reconstruction and compare it to the same surgical technique using standard autografts. Materials and Methods. Data were collected prospectively in 50 MPFL reconstructions. The first 27 underwent reconstruction using autograft; the following 23 patients were treated with FT. All patients were clinically and radiologically assessed and underwent pre- and post-operative scoring using the Kujala score, Bartlett score, Modified Tegner activity rating scale, SF 12 score and Lysholm score. Statistical significance was tested between groups using ANOVA with repeated measures. Results. There was no significant differences in the pre-operative scores between the FT and GT groups (p>0.05). Both groups showed significant improvement across all scoring modalities between pre- and post-operative periods 12, 24 and 48 months of follow-up (p<0.05). There were no significant differences in knee function scores between the GT and FT groups. Conclusion. The use of FT in MPFL reconstruction is safe and effective, it significantly improved patient's quality of life and related postoperative outcome measures. There were no significant differences in all knee scores compare to GT autografts. Tendon harvesting is unnecessary and FT is a feasible option for MPFL reconstruction

Medial patellofemoral ligament (MPFL) reconstruction is an effective procedure to address patellofemoral instability, however there remains no clear consensus on the optimum technique. Variations in patella tunnel and the use of patella fixation devices are reported in the literature, as are the associated complications of patella fracture and hardware irritation. We present the early results using a two tunnel, Endobutton free technique. 24 MPFL reconstructions (14 female, 10 male) were performed by a single surgeon, using two 3.5mm medial patellar tunnels exiting anteriorly and a looped, extra-synovial hamstring autograft. Femoral fixation was achieved using an non-absorbable interference screw. Mean age was 25.5 years, with a mean follow-up of 21.7 months. Mean Kujala scores were 60.8 preoperatively and 87.9 postoperatively (p<0.0001). No patient experienced further dislocation or patella fracture post-operatively. One patient required interference screw removal. The surgical technique presented has outcomes comparable with the literature. It requires a shorter tendon graft, and removes the need for a patellar fixation device, reducing potential irritation and cost

Recurrent patellar instability is common in young and active patients. Medial patellofemoral ligament (MPFL) reconstruction with a single bundle hamstring graft is one method of surgical treatment for this problem. This is a retrospective case series of patients who underwent MPFL reconstruction by a single specialist knee surgeon between January 2009 and July 2014. Data was collected prospectively for the purpose of service evaluation. Recorded data included gender, age, length of rehabilitation, complications, Knee Injury and Outcome Score (KOOS) and International Knee Documentation Score (IKDC). Data is expressed as mean (range). 108 knees (103 patients) were identified (56 female, 52 male) with a mean age of 24.5 years (12–58). Mean length of rehabilitation was 3.2 months (0–11 months). Three patients required further revision surgery for recurrent instability. KOOS and IKDC scores improved from 44 (4–86) and 38 (2–81), respectively before surgery, to 77 (49–100) and 69 (37–95) after rehabilitation. MPFL reconstruction with a single bundle hamstring graft produces a marked improvement in knee function with a low recurrence of instability

Patients with recurrent patella instability, who have an abnormal patellofemoral alignment (patella height or tibial tubercle-trochlear groove (TTTG) distance), benefit from tibial tubercle transfer along with medial patellofemoral ligament (MPFL) reconstruction. Between July 2008 and April 2013, 18 patients (21 knees) with recurrent patellar instability underwent combined MPFL reconstruction and tibial tubercle transfer. All patients had abnormal patellofemoral alignment in addition to MPFL insufficiency. 15 patients (16 knees) with a mean age of 24 years (16–41) had a mean follow up of 26 months (6–55). We assessed the outcome using KOOS, KUJALA, activity level and patient satisfaction scores. All patients had a stable patella. There was a significant improvement in outcome scores in 12 out of 15 patients. At final follow up KOOS score had improved from 68.25(44 to 93.9) to 77.05(48.8 to 96.4) and KUJALA score had improved from 63.3(41–88) to 78.06 (45 to 99). 9 patients showed excellent results and achieved at least a pre-injury level of activity. 4 of these had activity level better then preoperative level. 6 patients had a lower activity level than pre-injury (1 – ongoing physiotherapy, 1 – because of lack of confidence, and 4 – Life style modification). 14 patients were satisfied and happy to recommend this procedure. There were 3 postop complications, with 2 cases of stiffness and 1 case of non-union of the tibial tuberosity. Our prospective study has shown that restoration of tibial tubercle-trochlear groove index, Patella height and Medial Patellofemoral Ligament reconstruction yields good results in carefully selected patients

Purpose of Study:. Various techniques have been described and are still used for treating recurrent dislocation of the patella when conservative measures fail. Among them are distal, proximal and combined realignment techniques and lateral releases. Since being shown proof of the biomechanical importance of the medial patellofemoral ligament (MPFL) in patellofemoral instability, the reconstruction of the MPFL has gained in popularity. The objective of this paper is to present a case series with preliminary clinical results using the gracilis tendon to reconstruct the MPFL. Method:. Between 01/07 and 03/11 23 knees in 21 patients underwent reconstruction of the MPFL.4 of these patients had had previous surgery. Preoperatively the Caton Deschamps ratio using plain x-rays was worked out and the TT/TG distance was measured using CT scanning. Using these measurements as a guideline, 7 cases underwent a tibial tubercle transfer as an additional procedure. In 6 of the cases an additional cartilage procedure was required. The technique was simplified using intra-operative x-rays to achieve anatomical tunnel placement. Results:. The Tegner Activity Score was used to evaluate the patients preoperatively and at a minimum of 6 months postoperatively. The scores improved on average from 3,6 to 7,4. One patient had an extensor lag of 10 degrees at 3 months. This had normalised by 6 months. One patient had recurrence of her instability and required a revision MPFL reconstruction using an allograft. One patient had recurrent episodes of patella subluxation but no overt dislocation. Conclusion:. This case series gave good functional results using the Tegner Activity score. The procedure of MPFL reconstruction was effective in stabilising the patellae and in improving the symptoms of patellofemoral instability

The medial patellofemoral ligament (MPFL) has been recognised as the most important medial structure preventing lateral dislocation or subluxation of the patella (LeGrand 2007). After MPFL rupture the patella deviates from the optimal path resulting in an altered retropatellar pressure distribution. This may lead to an early degeneration with loss of function and need for endoprosthetic joint replacement. The goal of this study was to develop a dynamic knee-simulator to test the influence of ligament instabilities to patella-tracking under simulation of physiological quadriceps muscle loading. On 10 fresh-frozen cadaveric knees the quadriceps muscle was divided into five parts along their anatomic fibre orientation analogous to Farahmand 1998. The muscular loading was achieved by applying weights to each of the fife components in proportion to the cross sectional muscle area. A total of 175 N was connected to the muscles using modified industrial cable connecting systems [Lancier Calbe, Drensteinfurt/Germany]. A novel light digital patellar reference base (DRB) was developed and attached to the patella with four bone screws. On addition a femoral and tibial digital reference base was constructed and secured to these two bones. Position data of the patella, the femur and tibia was tracked by a conventional tracking system [Optotrak, NDI Europe]. The relative movement between femur and tibia (“flexion path”) and patella and femur (“patella tracking”) was recorded. For retropatellar pressure measurement a custom made sensor was introduced between the patella and femur [Pliance, Novel/Germany]. The sensor consists of 85 single pressure measuring cells. The robot-control-unit is liked to a force-torque sensor (hybrid method). The force free knee-flexion-path from 0° to 90° was calculated during three “passive path” measurements using this hybrid robotic method. The actual measurements followed with identical parameters. The 3D-patella position was recorded (six degrees of freedom) along with the corresponding retropatellar pressure distribution according to knee-flexion and medial forces (intact vs. cut MPFL). Measurements were performed for the intact knee (“native”), with muscular quadriceps loading, after opening the joint capsule and with introduced pressure sensor to differentiate each of their influences. The load free knee-flexion-path (“passive path”) could be calculated for all of the ten knees and was utilised as the basis for all dynamic measurements. There was no alteration of the “flexion-path”. Thus the measurements were only influenced by the variables “capsular joint opening,” “muscular quadriceps loading” and “MPFL-tension”. The custom made connections between the five quadriceps components and weights proved to be a secure way to prevent rupture due to the applied forces of up to 70 N during the average measuring time of 7.5 h/knee. Only on one knee the Vastus lateralis obliquus muscle ruptured proximally. All reference bases were 100% visible despite the knee flexion form 0°–90°. No loosening of the reference base screws occurred. Overall the combination of a robotic-assisted, force free dynamic knee-flexion under quadriceps simulation and 3D-patella-tracking seems to be a promising method to evaluate the biomechanical influences of ligaments on the human knee

INTRODUCTION. The medial patellofemoral ligament (MPFL) has been recognised as the most important medial structure preventing lateral dislocation or subluxation of the patella (LeGrand 2007). After MPFL rupture the patella deviates from the optimal path resulting in an altered retropatellar pressure distribution. This may lead to an early degeneration with loss of function and need for endoprosthetic joint replacement. The goal of this study was to obtain first data about retropatellar pressure distribution under simulation of physiological quadriceps muscle loading and evaluate the influence of ligament instabilities. MATERIALS AND METHOD. On ten fresh-frozen cadaveric knees the quadriceps muscle was divided into 5 parts along their anatomic fiber orientation analogous to Farahmand 1998. Muscular loading was achieved by applying weights to each of the five components in proportion to the cross sectional muscle area (total load 175 N). A custom made sensor was introduced between the patella and femur [Pliance, Novel / Germany]. The sensor consists of 85 single cells. The robot-control-unit is liked to a force-torque sensor. The force free knee-flexion-path from 0° to 90° was calculated during three “passive path” measurements. The actual measurements followed with identical parameters. At first, the retropatellar pressure distribution was recorded with intact ligaments (“native”). After cutting the MPFL the test was repeated. Then double bundle MPFL reconstruction (Schoettle 2009) was performed and the pressure distribution was obtained again. Minimum, mean and maximum pressures and forces were statistically compared in each of the three tested conditions (native Patella with intact MPFL, cut and reconstructed MPFL). We followed the hypothesis that MPFL reconstruction can restore native retropatellar pressure distribution. RESULTS. Mean retropatellar force measured in all conditions of the MPFL was 64.29 N [F. min. 0.06, F. max. 194.91, SD 66.99] N. Mean retropatellar pressure was 285.69 [P. min. 0.00, P. max. 923.64, SD 303.73] kPa. The mean retropatellar force increased with knee flexion from 35 N [0° flexion] to 75 N [90° flexion]. After cutting the MPFL mean force decreased in all degrees of flexion compared to the native state but mean pressure increased for the first 50° of flexion. Reconstruction of the MPFL did not restore native conditions. The mean pressure was only 3 N above the one of the cut MPFL. Regarding the entire retropatellar surface, maximum pressure decreased with increasing degrees of flexion from 330 kPa to 275 KPa. After cutting the MPFL, maximum pressure decreased about 60 kPa. MPFL reconstruction resulted in an increased maximum pressure (+ 10 kPa) in all degrees of flexion, but the values of the native state could not be achieved. To our knowledge this is the first experimental data of dynamic retropatellar pressure measurements on human cadaver knees in which a force free knee flexion is performed by an industrial robot under muscular quadriceps loading. There were no significant changes in retropatellar pressures after cutting the MPFL. In contrast to our hypothesis, MPFL reconstruction does not restore native conditions at this experimental setting