Medial Patellofemoral Ligament Reconstruction In Patients Research Articles

Medial Patellofemoral Ligament Reconstruction With Concomitant Tibial Tubercle Osteotomy

Background: Patellar instability, often associated with medial patellofemoral ligament rupture, is prevalent in adolescents. Risk factors include trochlear dysplasia, patella alta, abnormal patellar tilt, and increased tibial tubercle to trochlear groove (TT-TG) distance. Indication: A variety of surgical options are available for addressing patellar instability, and the selection of each technique should be tailored to the unique pathoanatomy of each patient. Medial patellofemoral ligament reconstruction (MPFLR) is indicated for patients with patellar instability, and tibial tubercle osteotomy (TTO) is indicated for patients with a TT-TG >20 mm. Technique Description: An anterior midline incision is performed to expose the patella, patellar tendon, and tibial tubercle. Diagnostic arthroscopy is performed to assess patellar engagement and cartilage integrity, followed by the TTO. Three guidewires are placed with 15° of obliquity, to guide a 6-cm osteotomy, from medial to lateral and from proximal to distal. A distal cortical hinge must be left intact. A 15-mm medial resection of the tibial tubercle is performed to avoid protrusion against the skin, which is followed by medialization of the tubercle and fixation with K-wires until dynamic testing ensures proper alignment and definitive fixation is achieved with cannulated headless screws. A lateral retinacular lengthening is performed to balance patellar forces. MPFLR is executed using a semitendinosus allograft. The graft is anchored to the patella and drawn through a surgically created plane to the medial femoral condyle. The femoral tunnel is created under fluoroscopy guidance, and the graft is then passed and secured. Graft tension and patellar mobility are adjusted according to dynamic testing. Once patellar stability is achieved and maintained through range of motion, the graft is then fixed. Results: Patients can expect improved clinical outcomes with a high return-to-sports rate following both isolated MPFLR and concomitant TTO. The combination of MPFLR + TTO significantly reduces revision rate, compared to isolated MPFLR in patients with increased TT-TG distance, and enhances postoperative patellofemoral tracking. Discussion/Conclusions: MPFLR + TTO improves patellofemoral tracking and corrects patellar instability, substantially improving postoperative outcomes compared to MPFLR alone. Patients with patellar instability and an increased TT-TG may be effectively treated with MPFLR + TTO. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Double-Level Knee Derotational Osteotomy Yields Better Postoperative Outcomes Than Tibial Tubercle Transfer Combined With Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Instability and Severe Malrotation

PurposeTo assess the postoperative outcomes of double level knee derotational osteotomy (KDRO) combined with medial patellofemoral ligament reconstruction (MPFLR), and to compare it with tibial tuber transfer (TTT) and MPFLR without derotational osteotomy in patients with recurrent patellar instability (RPI) and a marked torsional deformity. MethodsFrom March 2020 to December 2021, patients with torsion deformity (combined femoral torsion and tibial torsion ≥ 30°) were retrospectively included. The minimum follow-up time was 18 months. Patients received KDRO and MPFLR were categorized into KDRO group and patients received a combined TTT and MPFLR were categorized into control group. Preoperative and postoperative clinical symptoms, patient-reported outcomes (PROs) (Kujala, visual analogue scale [VAS], Lysholm, International Knee Documentation Committee [IKDC], Tegner, and Knee Injury and Osteoarthritis Outcome [KOOS] scores) and imaging parameters (femoral torsion, tibial torsion, patellar height, femoral trochlear dysplasia, congruence angle, patellar tilt angle, lateral patellar angle, lateral patellar translation, and tibial tubercle–trochlear groove distance) were analyzed. ResultsIn all, 36 patients were included with 18 in KDRO group and 18 in control group. The mean follow-up time was 30 (range 21-39) months. At the latest follow-up, no patient experienced re-dislocation in either group. Except for the femoral torsion and tibial torsion in the control group, postoperative imaging parameters were significantly reduced to the normal range. KDRO group has a lower patellar tilt angle (P=.043, effect size 0.64). All clinical scores in both groups significantly improved postoperatively. KDRO group has better functional scores than control group except the KOOS daily living activities subscore and the KOOS sports and recreation subscore. More proportions of patients in KDRO group met the minimal clinically important difference (MCID) for most PROs than control group. Eight patients (44%) in the control group complained of postoperative anterior knee pain, compared with 1 patient (6%) in KDRO group (P=.018). ConclusionKDRO combined with MPFLR was associated with better postoperative outcomes than TTT combined with MPFLR in patients with RPI and a torsion deformity.

The Adductor Sling Technique for Pediatric Medial Patellofemoral Ligament Reconstruction Better Resists Dislocation Loads When Compared With Adductor Transfer at Time Zero in a Cadaveric Model

To characterize the ability of the intact medial patellofemoral ligament (MPFL) and the adductor transfer and adductor sling MPFL reconstruction techniques to resist subluxation and dislocation in a cadaveric model. Nine fresh-frozen cadaveric knees were placed on a custom testing fixture with the femur fixed parallel to the floor, the tibia placed in 20° of flexion, and the patella attached to a load cell. The patella was displaced laterally, and subluxation load (in newtons), dislocation load (in newtons), maximum failure load (in newtons), patellar displacement at failure, and mode of failure were recorded. Testing was conducted with the MPFL intact and after the adductor sling and adductor transfer reconstruction techniques. Statistical analysis was completed using 1-way repeated-measures analysis of variance with the Holm-Šidák post hoc test. The subluxation load was not significantly different between groups. The native MPFL dislocation load was significantly higher than the dislocation loads of both reconstruction techniques, but no significant difference between the dislocation loads of the 2 reconstruction techniques occurred. The native MPFL failure load was significantly higher than the failure loads of both reconstruction techniques. The adductor sling failure load was significantly higher than the adductor transfer failure load. The mode of failure varied across groups. The native MPFL failed by femoral avulsion, patellar avulsion, and midsubstance tear. The main mode of failure for adductor transfer was pullout, whereas failure for the adductor sling technique most often occurred at the sutures. Most of the native MPFLs and all adductor sling reconstructions failed after dislocation. The adductor transfer reconstructions were much more variable, with failures spanning from before subluxation through dislocation. Our cadaveric model showed that neither the adductor transfer technique nor the adductor sling technique restored failure load to that of the native condition. There was no significant difference in the subluxation or dislocation loads between the 2 MPFL reconstructions, but the adductor sling technique resulted in a higher load to failure. The adductor transfer technique frequently failed before subluxation or dislocation when compared with the adductor sling technique and the native MPFL. The best technique for MPFL reconstruction in patients with open physes is a topic of debate. Given the long-term consequences of MPFL injury and potential for growth plate disturbance, it is important to study MPFL reconstruction techniques thoroughly, including in the laboratory setting.

Revision Medial Patellofemoral Ligament Reconstruction for Recurrent Instability After Patellofemoral Arthroplasty

Recurrent patellar instability is a rare complication after patellofemoral arthroplasty (PFA) and usually involves a traumatic injury. Medial patellofemoral ligament (MPFL) reconstruction after arthroplasty is a complicated and technically challenging surgical procedure because the lack of patellar bone stock due to resurfacing significantly increases the risk of patellar fracture. We present our surgical technique for revision MPFL reconstruction for recurrent instability after PFA. This technical note describes the use of 1.8-mm all-suture anchors for revision MPFL reconstruction in patients with decreased patellar bone stock after PFA. This technique reduces the risk of patellar fracture without compromising the integrity of the MPFL graft.

Results of Medial Patellofemoral Ligament Reconstruction with and without Tibial Tubercle Transfer in Patellar Instability: A Systematic Review and Meta-Analysis.

The optimal surgical intervention for lateral patellar instability remains a topic of controversy despite satisfactory clinical outcomes and low re-dislocation rates reported in numerous studies following medial patellofemoral ligament reconstruction (MPFLR) with and without tibial tubercle transfer (TTT). The purpose of this systematic review and meta-analysis is to investigate the hypothesis that combining MPFLR with TTT provides reduced complication rates and improved clinical outcomes to isolated MPFLR in patients with lateral patellar instability. We conducted a comprehensive systematic review and meta-analysis of comparative trials involving MPFLR with and without TTT, sourcing data from PubMed, the Cochrane Library, Embase, and Web of Science. The primary clinical outcomes analyzed included the Kujala score, the Lysholm score, complication rates, and the Caton-Deschamps index (CDI). Random or fixed effects were used for the meta-analysis. Postoperatively, there were no significant differences observed in the Kujala and Lysholm scores between MPFLR and MPFLR + TTT (p = 0.053). At the final follow-up, the CDI had decreased 0.015 (95% CI -0.044, 0.013; p = 0.289) points in the MPFLR group, with no statistical significance. In contrast, the MPFLR + TTT group demonstrated a significant decrease of 0.207 (95% CI -0.240, -0.174; p = 0.000) points in CDI. Notably, the complication rate was higher in the MPFLR + TTT group compared to the MPFLR-only group (RR = 2.472; 95% CI 1.638, 3.731; p = 0.000). Both MPFLR and MPFLR + TTT procedures yield significant improvements in the Kujala and Lysholm scores. However, the MPFLR + TTT approach results in an apparent improvement in CDI and corrects patellar maltracking, particularly in cases involving high tibial tuberosity-trochlear groove (TT-TG) (>20 mm) or patella alta (CDI > 1.2), while MPFLR alone cannot. It is essential to consider the higher complication rate of MPFLR + TTT, which suggests that MPFLR alone may be sufficient for patients without high TT-TG or patella alta.

Predictors of Graft Failure After Primary Medial Patellofemoral Ligament Reconstruction.

The tibiofemoral rotation angle has been found to be higher in patients with recurrent patellar dislocations (RPDs) than in healthy people; however, little is known about the clinical significance of this finding. To determine whether an increased tibiofemoral rotation angle is associated with graft failure after primary medial patellofemoral ligament reconstruction (MPFL-R) and to investigate the role of the tibiofemoral rotation angle in predicting MPFL-R failure in patients with RPDs. Case-control study; Level of evidence, 3. We retrospectively analyzed the records of 632 consecutive patients with clinically diagnosed RPDs from 2011 to 2018. Postoperative stress radiography of the patellofemoral joint was performed to identify whether the graft failed. After a review, 33 patients who showed MPFL-R failure were allocated to the failure group. They were matched 1:2 to 66 participants who underwent successful MPFL-R (control group). The cutoff value and area under the curve (AUC) of the tibiofemoral rotation angle for predicting graft failure after primary MPFL-R were determined, and the risk factors for MPFL-R failure were assessed by multivariate logistic regression analysis. The tibiofemoral rotation angle was significantly higher in the failure group than in the control group (16.4° ± 5.6° vs 6.4° ± 4.5°, respectively; P < .001). The cutoff value of the tibiofemoral rotation angle for predicting graft failure was 12.3° (sensitivity, 81.8%; specificity, 89.4%; AUC, 0.920). Overall, 3 risk factors for MPFL-R failure were determined: excessive tibiofemoral rotation (≥12.3°) (odds ratio [OR], 13.159 [95% CI, 2.469-70.139]; P = .003), a preoperative high-grade J-sign (OR, 7.674 [95% CI, 1.232-47.809]; P = .029), and a femoral tunnel malposition (OR, 6.976 [95% CI, 1.077-45.187]; P = .042). In this study, excessive tibiofemoral rotation, a preoperative high-grade J-sign, and a femoral tunnel malposition were identified as risk factors for graft failure after primary MPFL-R in patients with RPDs. More importantly, excessive tibiofemoral rotation ( ≥ 12.3°) may predict the failure of primary MPFL-R, which can help surgeons easily identify high-risk patients of MPFL-R failure before surgery.

Lateral retinacular release in concordance with medial patellofemoral ligament reconstruction in patients with recurrent patellar instability: A computational model

BackgroundThe aim of this study was to develop and validate a finite element (FE) model of the patellofemoral joint to analyze the biomechanics of lateral retinacular release after medial patellofemoral ligament (MPFL) reconstruction in patellar malalignment (increased tibial tubercle–trochlear groove distance (TT-TG)). We hypothesized that lateral retinacular release is not appropriate in patellar instability addressed by MPFL reconstruction due to decreased lateral stability and inappropriate adjustment in patellofemoral contact pressures. MethodsA FE in-silico model of the patellofemoral joint was developed and validated. The model was used analyze the effect of lateral retinacular release in association with MPFL reconstruction on patellofemoral contact pressures, contact area, and lateral patellar displacement during knee flexion. ResultsMPFL reconstruction alone results in restoration of patellofemoral contact pressures throughout the entire range of motion (0–90°), mimicking the results from healthy condition. The addition of the lateral retinacular release to the MPFL reconstruction resulted in significant reductions in both patellofemoral contact pressure and contact area. Lateral retinacular release resulted in more lateral patellar displacement during the mid-flexion knee range of motion. ConclusionsCombination of lateral retinacular release with MPFL reconstruction in patients with increased TT-TG is not recommended as MPFL reconstruction alone for first-line management of recurrent patellar instability offers a greater biomechanical advantage and restoration of contact forces to resemble that of the healthy knee. The presented biomechanical data outlines the effect of concomitant MPFL reconstruction and lateral retinacular release to help guide surgical planning for patients with recurrent patellar instability due to malalignment.

Influence of Patellofemoral Anatomy on Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability.

Background:Patella alta and elevated tibial tubercle–trochlear groove (TT-TG) distance can predispose patients to lateral patellar dislocations and recurrent instability. Their influence on patient-reported outcomes (PROs) after medial patellofemoral ligament (MPFL) reconstruction is less clear.Hypothesis:We hypothesized that neither moderately increased TT-TG distance nor patella alta would negatively affect PROs after isolated MPFL reconstruction in patients with relatively normal patellar tracking (no large J-sign).Study Design:Cohort study; Level of evidence, 3.Methods:We identified patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. The decision to perform an isolated MPFL reconstruction was at the discretion of the operating surgeon but was not performed in the setting of a large J-sign. Patient characteristics and surgical details were collected, and patients completed the Norwich Patellar Instability Score, Knee injury and Osteoarthritis Outcome Score, and Marx activity score. Patellar height (Caton-Deschamps Index [CDI]) was assessed on preoperative lateral radiographs, and TT-TG distance was measured on preoperative axial magnetic resonance imaging (MRI) scans. Patients were grouped based on CDI and TT-TG distance, and outcomes were compared. Linear regression modeling was performed to determine whether patella alta or elevated TT-TG distance was associated with poorer PRO scores.Results:Of 165 knees in 152 patients who underwent isolated MPFL reconstruction, 115 patients (125 knees; 76%) with minimum 1-year follow-up were contacted at a mean of 5.2 years after surgery. Recurrent dislocation occurred in 5 of 125 knees (4%). Preoperative radiographs were available in 111 knees (89%), and preoperative MRI scans were available in 89 knees (71%). Mean CDI was 1.13, and 35% had a CDI ≥1.20. Mean TT-TG distance was 17.5 mm, and 26% had a TT-TG distance >20 mm. After adjusting for patient age, sex, body mass index, and graft choice, we observed that neither patella alta nor elevated TT-TG distance were associated with poorer PROs.Conclusion:Isolated MPFL reconstruction in the setting of moderately elevated TT-TG distance or patella alta was not associated with worse PROs in this cohort with relatively normal patellar tracking (no large J-sign).

Isolated MPFL reconstruction for recurrent lateral patellar instability in patients with TT-TG distance &lt;25 mm: A calculated safe risk!

Objectives: The objectives of the study were to describe the surgical technique of our modification of isolated medial patellofemoral ligament (MPFL) reconstruction, in patients with patellar instability. As per literature, isolated MPFL reconstruction is advocated if tibial tubercle-trochlear groove (TTTG) &lt;20 mm. Our study proposes isolated MPFL reconstruction in patients with TT-TG &lt;25 mm and aims to determine any predisposing anatomic variants to aid in the treatment algorithm. Materials and Methods: A retrospective analysis of 52 patients with patellar instability (TT-TG &lt;25 mm), who underwent isolated MPFL reconstruction was undertaken. The study population was divided into two groups; TT-TG &lt;20 mm and TT-TG = 20–24 mm. Both groups were assessed radiologically and on the basis of clinical and functional outcome (KUJALA score), over 5-year follow-up period. Results: The mean age of the study population was 21.98 years, with a female (63.5%) majority. Among the 52 patients included in the study, 39 patients (75%) had TT-TG &lt;20 mm and 13 patients (25%) had TT-TG = 20–24 mm. We noticed statistically significant improvement in both groups with respect to clinical and functional outcome, with no reported complications. None of the patients had patella alta or high grades of trochlear dysplasia. Conclusion: MPFL reconstruction without concomitant bony procedures can be safely performed in patients with a TT-TG &lt;25 mm, in the absence of patella alta or high-grade trochlear dysplasia. Our modification of isolated MPFL reconstruction has shown excellent long-term results. In addition, our technique uses only a single interference screw, thereby reducing cost of surgery and implant hardware.

The presence of a preoperative high-grade J-sign and femoral tunnel malposition are associated with residual graft laxity after MPFL reconstruction.

The purpose of this study was to analyse the risk factors associated with residual graft laxity after medial patellofemoral ligament reconstruction (MPFL-R) in patients with recurrent patellar dislocation (RPD). A total of 312 consecutive patients (354 knees) with clinically diagnosed RPD who underwent MPFL-R from 2011 to 2015 were retrospectively analysed. Postoperative MPFL graft stability was assessed with patellofemoral stress radiography, and if the patellar central ridge surpassed the apex of the lateral femoral trochlea, the reconstructed MPFL was defined as having residual graft laxity. Finally, 15 patients who exhibited MPFL residual graft laxity (study group) were matched in a 1:2 fashion to 30 control participants (control group), who showed a normal postoperative patellar stability on stress radiography. Preoperative three-dimensional computed tomography (3D-CT) was used to identify patients with a high-grade J-sign. Femoral tunnel position was assessed using 3D-CT to identify cases with femoral tunnel malposition. Potential predictors of MPFL residual graft laxity, including age, sex, a preoperative high-grade J-sign, femoral tunnel malposition, and several radiological parameters, were assessed by logistic regression analysis. A preoperative high-grade J-sign was identified in 66.7% of the study group, which was significantly higher than that the 13.3% in the control group (P = 0.001). In addition, the presence of a preoperative high-grade J-sign (odds ratio, 11.9 [95% CI, 1.7-82.8]; P = 0.012) and femoral tunnel malposition (odds ratio, 8.2 [95% CI, 1.2-58.0]; P = 0.036) were determined to be independent risk factors associated with residual graft laxity after MPFL-R. The presence of a preoperative high-grade J-sign and femoral tunnel malposition are associated with residual graft laxity after MPFL-R in patients with RPD. These results may provide additional information for counselling patients on residual graft laxity after MPFL-R. Level III.

Anatomical and Biomechanical properties of MPFL reconstruction technique using Adductor Magnus tendon graft

Aims and Objectives:The main goal of the presented study was to evaluate the anatomical and biomechanical properties of the proposed surgical technique for anatomical Medial Patellofemoral ligament (MPFL) reconstruction using the flat Adductor tendon (AT) graft in order to primarily determine its overall plausibility and application potential, as well as to reveal the main risks and pitfalls of the technique.Materials and Methods:Anatomical descriptive evaluation, followed by biomechanical testing of the proposed AT- MPFL reconstruction was conducted on 12 fresh frozen human cadaveric knees. The morphological and topographical features of the AT and native MPFL were reported. The biomechanical tests were performed in order to determine the strength and resistance to maximum loading force of the reconstruction. The construct was placed in an uniaxial testing machine and cyclically loaded 500 times between 5 and 50N, followed by load to failure, measuring the maximum elongation, stiffness and maximum load respectively.Results:Regarding the anatomical evaluation of the structures in focus, several findings have been reported. The mean length of the tendon was found to be 12,59±1,54cm, the mean distance between the insertion on the Adductor tubercule and Hiatus was measured at 10,83±1,27cm, exceeding the mean desired length of the graft, found at 7,54±0,45cm by 2,43±0,56cm. The desired length of the graft was based on the measured length of the native MPFL with additional ±25-30mm of the tendon that allows for intraoperative length changes and different means of patellar fixation depending on the surgeons preference. The insertion of the Adductor tendon on the Adductor tubercule was found to be superior and posterior to the insertion of the native MPFL. The distal portion of AT was found to be consisted of two distinct parts with varying fiber orientation, the tendinous and the membranous part. After cyclic load, the maximum elongation was reported at 1,9 ± 0,4mm. The mean stiffness and load to failure of the construct were measured at 26,2±7,6N/mm and 148,74±22,01N. The graft failed at the patellar insertion site in two of the tested specimens and at the femoral insertion site in the remaining 10.Conclusion:Due to its advantageous anatomical and topographical aspects, as well as adequate biomechanical properties, the Adductor tendon graft caries a high utilization potential for MPFL reconstruction. Application that allows for primarily soft tissue fixation on the patella, in addition to absence of femoral drill holes with consequently no risk of injury to the physis, makes the AT graft choice a preferable option when considering MPFL reconstruction in patients with open growth plates. Even though it includes graft and methods of fixation alternative to the traditionally used techniques, this reconstruction is not exclusively predetermined for the skeletally immature patients and has a high application potential for the older patient population as well.

Does graft choice influence the outcome of MPFL reconstruction in patients with patellofemoral instability and increased TT-TG distance?

A systematic review of the literature was conducted to determine the effect of graft choice on patient outcomes in patients undergoing a medial patellofemoral ligament (MPFL) reconstruction with concomitant tibial tubercle transfer (TTT). Utilizing the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and QUORUM (Quality of Reporting of Meta-Analyses) protocol, a systematic search identified and analyzed the published literature pertaining to MPFL reconstruction with TTT. The literature search yielded eight eligible studies with a total of 183 knees treated with a MPFL reconstruction with TTT procedure involving either a gracilis autograft, a semitendinosus autograft, or a medial retinaculum autograft. The eight studies varied on the outcome measures reported, but the outcome measures most consistently used and assessed in this systematic review included the complication rate, postoperative instability rate, Kujala score, Lysholm score, International Knee Documentation Committee functional evaluation form, and the Tegner activity scale. Our study found that patients undergoing MPFL reconstruction with TTT resulted in good overall patient outcomes. No statistical difference was found between the graft choices on any of the outcome measures. While MPFL reconstruction with TTT resulted in low to moderate complication rates and low postoperative patellofemoral instability rates, one potential explanation for the postoperative instability and knee stiffness observed may derive from graft choice. Future research may consider addressing the effect of graft choice on improperly tensioned grafts and overmedialized TTTs.

Lateral retinacular release is not recommended in association to MPFL reconstruction in recurrent patellar dislocation

Reconstruction of the medial patellofemoral ligament (MPFL) has become the gold standard for the treatment of the recurrent patellar dislocation (RPD). Lateral retinacular release can be performed in association with MPFL reconstruction, but the effect on outcomes is not clear. To evaluate the effect of lateral release on outcomes following MPFL reconstruction is the aim of this study. It is hypothesized that isolated MPFL reconstruction was not inferior to MPFL reconstruction and lateral retinacular release in terms of IKDC subjective score and patellar tilt (PT). Patients between ages 18 and 45 scheduled to undergo MPFL reconstruction without an associated bony procedure (tibial tubercle osteotomy or trochleoplasty) were randomized to isolated MPFL reconstruction or MPFL reconstruction (no LRR group) and arthroscopic LRR (LRR group). Evaluation criteria were subjective IKDC score as the primary outcome and PT evaluated with a CT-scan. PT was evaluated with the quadriceps relaxed (PTQR) and contracted (PTQC). Of 43 patients included in the trial, 7 were lost of follow-up, 3 were not able to complete evaluation because of medical reasons, and 33 patients were evaluated with a minimum of 12 months and a median follow-up of 24 (12-60)months. The average subjective IKDC score was at 86 ± 20 (29-94) in the LRR group and 82 ± 15 (39-95) in the no LRR group (p = 0.45). The PTQR was at 22° ± 7° (13-37) in the LRR group and 21 ± 10 (4-37) in the no LRR group (n.s.). The PTQC was at 27° ± 9° (12-40) in the LRR group and 25 ± 12 (5-45) in the no LRR group (n.s.). No complications were noted in either group. No significant differences were found in subjective IKDC score or patellar tilt based on the addition of an arthroscopic LRR to an MPFL reconstruction in patients with RPD not undergoing associated bony procedures. There is no indication to a systematic lateral retinacular release in association with MPFL reconstruction in the treatment of RPD. II.

Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and meta-analysis.

Many studies have reported satisfactory clinical outcomes and low redislocation rates after reconstruction of the medial patellofemoral ligament (MPFL) for the treatment of lateral patellar instability. Despite uncorrected severe trochlear dysplasia (Dejour type B to D) being acknowledged as a major reason for less favourable clinical outcomes and a higher incidence of patellar redislocations after an isolated MPFL reconstruction, the evidence for a deepening trochleoplasty procedure remains scarce in the current literature. The hypothesis of this systematic review and meta-analysis was that a deepening trochleoplasty in combination with an a la carte extensor apparatus balancing procedure provides lower redislocation rates and superior clinical outcomes than isolated MPFL reconstruction in patients with lateral patellar instability caused by severe trochlear dysplasia. A systematic review of the literature was conducted using specific inclusion and exclusion criteria for clinical studies reporting index operations (trochleoplasty and MPFL reconstruction) for the treatment of patellar instability caused by severe trochlear dysplasia. The Kujala score was analysed as the primary clinical outcome parameter in a random effects meta-analysis. Ten uncontrolled studies with a total of 407 knees (374 patients) were included in this analysis. The MPFL group comprised 4 studies with a total of 221 knees (210 patients), and the trochleoplasty group comprised 6 studies with a total of 186 knees (164 patients). The mean preoperative Kujala score ranged between 50.4 and 70.5 in the MPFL group and between 44.8 and 75.1 in the trochleoplasty group. The pooled Kujala score increased significantly by 26.4 (95% CI 21.4, 31.3; P<0.00001) points in the MPFL group and by 26.2 (95% CI 19.8, 32.7; P<0.00001) points in the trochleoplasty group. The post-operative patellar redislocation/subluxation rate was 7% in the MPFL group and 2.1% in the trochleoplasty group. This analysis found significant post-operative improvements in patient-reported outcomes for patients undergoing both an MPFL reconstruction and in those undergoing a trochleoplasty plus an individual extensor apparatus balancing procedure when assessed using the Kujala score. The likelihood of preventing the patella from subsequent post-operative redislocation/subluxation was, however, greater in patients who underwent trochleoplasty plus extensor balancing. IV.

Treatment of patellar instability in a case of hereditary onycho-osteodysplasia (nail-patella syndrome) with medial patellofemoral ligament reconstruction: A case report.

Hereditary onycho-osteodysplasia, also known as nail-patella syndrome (NPS), is a rare genetic disorder that is primarily characterized by poorly developed nails and patella. Patients with NPS frequently suffer from patellar instability that requires surgical management. The present case report describes a 25-year-old man with NPS. The patient presented with left knee pain and was found to have recurrent left patellar dislocation. The knee pain was first reported 1-year after a minor knee trauma incident. Following complete evaluation, a diagnosis of NPS was reached. The patient underwent surgical intervention using medial patellofemoral ligament (MPFL) reconstruction with a gracilis tendon autograft looped through two transverse 3.2-mm drill holes in the patella and fixed at the natural MPFL insertion site on the medial femoral condyle with an interference screw. The surgery resulted in stabilization of the patella in the femoral trochlea and the patient did not have any subsequent dislocations or subluxations. The patient had an excellent range of knee movement in the follow-up period. This case indicates that MPFL reconstruction in patients with patellar dislocation secondary to NPS can successfully restore normal patellar tracking and result in good range of movement and functional activity.

Knee biomechanics during walking in recurrent lateral patellar dislocation are normalized by 1year after medial patellofemoral ligament reconstruction.

Gait kinematics and kinetics of the knee before and after medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent lateral patellar dislocation (RPD) are unknown. The purpose of this study was to measure knee kinematics and kinetics during gait before and 1year after anatomical MPFL reconstruction in patients with RPD and compare the results to healthy individuals. Eleven RPD patients were treated using an anatomical MPFL reconstruction procedure. Gait analysis was conducted before and at 3, 6, and 12months after surgery. For comparison, 15 healthy volunteers with no history of orthopaedic problems in their lower limbs were included as the control group. Knee kinematics and kinetics were analysed during gait. Before surgery, the internal knee extension moment in RPD patients was significantly lower than in controls (P=0.025). At 3months post-operatively, there was an additional decrease in knee extension moment compared to before surgery, and so it was still significantly lower than in the control group (P<0.01). Oneyear post-operatively, knee extension moment in the RPD group was significantly increased compared to 3months post-operatively (P<0.01). The knee flexion angle in the early stance phase in the RPD group at 3months post-operatively was significantly lower than that of controls (P<0.01). Knee kinematics and kinetics were similar to that of controls 1year after surgery. Initially, RPD patients had lower knee extension moments during gait compared with controls, but by 1year after MPFL reconstruction, knee kinematics and kinetics of gait in the RPD patients had returned to normal. These observations indicate that MPFL reconstruction may help to delay prospective knee OA as long as possible by restoring the conformation of the patellofemoral joint and gait biomechanics by surgery.

Clinical outcomes of medial patellofemoral ligament reconstruction in patients with an increased tibial tuberosity–trochlear groove distance

Medial patellofemoral ligament (MPFL) reconstruction is performed to treat recurrent patellar dislocation (RPD). However, the effectiveness of MPFL reconstruction in patients with a severely lateralised tibial tuberosity remains unknown. In this study, the clinical outcomes of MPFL reconstruction in patients with an increased tibial tuberosity-trochlear groove (TT-TG) distance were examined. A total of thirty-four patients who underwent MPFL reconstruction for RPD were retrospectively examined. Nineteen patients with a TT-TG distance of >20 mm (increased TT-TG distance group) were compared with 15 patients with a TT-TG distance of <20 mm (control group). Clinical outcomes of MPFL reconstruction were evaluated by occurrence of re-dislocation, Crosby and Insall grading system, apprehension sign, and Kujala and Lysholm scores. None of the patients reported re-dislocation. Apprehension sign remained in three patients in the increased TT-TG distance group and in one patient in the control group. According to the Crosby and Insall grading system, 9 patients (47%) were excellent, 9 (47%) were good, and 1 (5%) was fair to poor in the increased TT-TG distance group, while 6 (40%) were excellent and 9 (60%) were good in the control group. Kujala and Lysholm scores were significantly improved post-operatively in both groups. No significant correlations were observed between TT-TG distance and post-operative Kujala or Lysholm score. Overall clinical outcomes of MPFL reconstruction were favourable even in patients with an increased TT-TG distance. TT-TG distance of >20 mm may not be an absolute indication for medialisation of the tibial tuberosity when performing MPFL reconstruction. Case-control study, Level III.