Combining tibial tubercle osteotomy with medial patellofemoral ligament reconstruction often yields better outcomes in treating patellofemoral instability: a systematic review and meta-analysis of case-control studies.

PURPOSE: Tibial tubercle osteotomy (TTO) is often employed for certain patellofemoral instability (PFI) cases, though its indications and effectiveness are not widely accepted. This systematic review gathers recent studies comparing isolated medial patellofemoral ligament reconstruction (iMPFLR) to MPFLR combined with TTO in managing PFI and to offer recommendations for clinicians when selecting TTO. This review proposes that MPFLR combined with TTO is superior to iMPFLR and that the combined procedure does not increase the incidence of postoperative complications. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020), extensive searches were performed on August 20, 2024, across PubMed/Medline, Embase, and Cochrane databases to locate relevant studies. Data on research protocols, participant characteristics (including epidemiological and radiographic features), functional scores, and complications were collected and examined. A meta-analysis was conducted to compare the outcomes between the two surgical techniques. RESULTS: This systematic review analyzed 10 studies involving 715 participants, divided into a control group (which underwent iMPFLR) and an experimental group (which underwent MPFLR combined with TTO). In the control group, the incidence of severe trochlear dysplasia before surgery was 68.3% (95% CI [67.3-69.3%]), and the mean preoperative tibial tubercle to trochlear groove distance (TT-TG) was 16.1 mm (95% CI [15.8-16.3]). In the experimental group, both were respectively 79.1% (95% CI [77.5-80.7]) and 20.2 mm (95% CI [20.0-20.4]). Eight studies (80%) reported postoperative Kujala scores, with an average score of 85.1 (95% CI [84.4-85.9]) for the control group and 85.4 (95% CI [84.9-85.9]) for the experimental group (I²=22.7%). Four studies (40%) reported postoperative Lysholm scores, with an average score of 89.4 (95% CI [88.9-89.9]) for the control group and 89.1 (95% CI [89.0-89.3]) for the experimental group (I²=0%). The mean surgical failure rate for the control group was 5.1% (95% CI [4.7-5.6%]), compared to 3.2% (95% CI [3.0-3.4%]) for the experimental group, with an odds ratio (OR) of 2.18 (95% CI [1.05-4.53], I²=0%, p = 0.738). The rate of secondary surgeries in the control group was 1.9% (95% CI [1.6-2.2]), while in the experimental group it was 10.7% (95% CI [9.4-12.1]), with an OR of 0.12 (95% CI [0.03-0.54], I²=63.1%, p = 0.028). CONCLUSION: The combination of MPFLR and TTO for treating PFI yields knee joint function comparable to that achieved with MPFLR alone. The approach does not elevate the failure rate of the surgery or the incidence of other adverse events. However, the combined approach may prolong the postoperative rehabilitation process and typically requires removal of internal fixation devices, resulting in a higher rate of secondary surgeries.

Patellofemoral Instability in the Pediatric and Adolescent Population: From Causes to Treatments.

BACKGROUND: Patella instability is one of the most common knee injuries in the adolescent patient. There are several pathoanatomic risk factors which should be assessed via several modalities, including X-rays, magnetic resonance imaging (MRI), or even CT scan. OBJECTIVES: We intend to review these risk factors along with the nonsurgical and surgical techniques used to prevent recurrent dislocations. METHODS: We completed an extensive review of the recent literature concerning pediatric and adolescent patellar dislocation and subsequent treatment modalities. RESULTS: We review in detail the risk factors such as patella alta, trochlear dysplasia, lateralization of the tibial tubercle or medialization of the trochlear groove (increased tibial tubercle to trochlear groove (TT-TG) distance), lower limb malalignment, excessive femoral anteversion and/or tibial torsion, and hyperlaxity. There are classification systems for dislocators, and a natural progression of instability that patients often proceed through. Only after a patient has continued to dislocate after bracing and physical therapy is surgical treatment considered. Surgical techniques vary, with the workhorse being the medial patellofemoral ligament (MPFL) reconstruction. However, there are a variety of other techniques which add onto this procedure to address other anatomic risk factors. These include the tibial tubercle osteotomy to address a large TT-TG distance or trochleoplasty to address the lack of a trochlear groove. CONCLUSIONS: Nonsurgical and surgical treatments for patella dislocators are tailored to the pathoanatomic risk factors in each patient.

Finite element analysis of the knee joint: a computational tool to analyze the combined behavior after treatment of torn ligaments and menisci in the human knee joint.

Finite element analysis (FEA) is a fundamental tool that can be used in the orthopaedic world to simulate and analyze the behaviour of different surgical procedures. It is important to be aware that removing more than 20% of the meniscus could increase the shear stress in the cartilage and enlarge the risk of knee joint degeneration. In this fact, the maximal shear stress value in the medial cartilage increased up to 225% from 0.15 MPa to 0.5 MPa after medial meniscectomy. Also, meniscal root repair can improve meniscal biomechanics and potentially reduce the risk of osteoarthritis, even in cases of a loose repair. FEA has been used to better understand the biomechanical role of cruciate ligaments in the knee joint. ACLr with bone-patellar tendon-bone graft at 60 N of pretension and double-bundle PCLr were closer to that of a native knee in terms of biomechanics. The addition of a lateral extra-articular augmentation technique can reduce 50% of tibial translation and internal rotation, protecting the graft and minimizing the risk of re-rupture. Interestingly, anatomic and non-anatomic medial patellofemoral ligament reconstruction increased the pressure applied to the patellofemoral joint by increasing patellar contact pressure to 0.14 MPa at 30° of knee flexion using the semitendinosus as a graft. After all the advances in medical imaging technologies, future studies should take into consideration patient-specific data on both anatomy and mechanics, in order to better personalize the experimental model.

Clinical and Radiological Outcomes After Isolated Double-Bundle Medial Patellofemoral Ligament Reconstruction: A 5-Year Analysis.

Background: There are few studies that have examined clinical and radiological outcomes at 5 years after isolated medial patellofemoral ligament (MPFL) reconstruction. To date, midterm outcomes after isolated double-bundle (DB) MPFL reconstruction are not well known. Hypothesis: Isolated DB MPFL reconstruction using a patellar suture anchor technique would lead to improved functional scores and radiological findings, and these improvements would remain stable over the 5-year postoperative period. Study Design: Case series; Level of evidence, 4. Methods: Isolated MPFL reconstruction was performed in patients with recurrent patellar instability between March 2013 and February 2017. Clinical and functional evaluations were performed via an interview using the Kujala, Lysholm, and Tegner scores preoperatively and at 6, 12, 24, and 60 months postoperatively. Radiographs were taken preoperatively, immediately postoperatively, and at 24 and 60 months after surgery. Radiographic assessments included measuring the modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle. Results: A total of 31 patients (31 knees) underwent isolated MPFL reconstruction; 4 patients did not complete 5-year follow-up, and thus, 27 patients (27 knees) were enrolled in the study. The mean age at the time of surgery was 22.0 ± 6.4 years (range, 14-32 years). All clinical and functional scores significantly improved in the first 2 years (P < .001), with the mean Kujala, Lysholm, and Tegner scores improving from 52.7 to 90.7, 49.6 to 92.7, and 2.9 to 5.1, respectively. There was no significant difference in scores between 2- and 5-year follow-up. All radiographic parameters significantly improved between preoperatively and immediately postoperatively (P < .001), with mean values for the modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle improving from 1.7° to 1.6°, 5.7° to -6.6°, and 3.0° to 5.9°, respectively. No significant differences were observed in radiographic measurements between the postoperative time points. No patients experienced a patellar redislocation or fracture. Conclusion: The prospective analysis of isolated DB MPFL reconstruction at 5-year follow-up showed that clinical and radiological outcomes significantly improved postoperatively and were maintained to 5 years. These midterm results suggest that isolated DB MPFL reconstruction is an effective treatment option for patients with patellar instability.

Comparison of Clinical and Radiological Outcomes With Body Mass Index After Medial Patellofemoral Ligament Reconstruction.

Background: Medial patellofemoral ligament (MPFL) reconstruction is a commonly employed surgical approach for recurrent patellar dislocation. However, the impact of elevated body mass index (BMI) on postoperative complication rates remains controversial. Purpose: To compare the clinical, radiographic, and functional outcomes of patients with normal BMI (18.5-24.9 kg/m2) and those with elevated BMI (≥25 kg/m2) who underwent MPFL reconstruction for recurrent acquired lateral traumatic patellar dislocation. Study Design: Cohort Study; Level of evidence, 3. Methods: A total of 70 patients who underwent MPFL reconstruction for recurrent patellar dislocation were included in this study. Patients with recurrent patellar dislocation were categorized into 2 groups based on their BMI: the normal BMI group and the elevated BMI group. Functional scores (Lysholm, International Knee Documentation Committee [IKDC], Tegner, and Kujala scores) and radiological measurements (patellar tilt angle, patellofemoral trochlear congruence, lateral patellofemoral angle, and lateral patellar displacement) were evaluated both preoperatively and at the last follow-up. The occurrence of postoperative complications at the last follow-up was also recorded. Differences in functional scores and radiological parameters before and after surgery were analyzed with paired-samples t tests or Wilcoxon signed-rank tests. Comparisons between groups were conducted using independent-samples t tests or the Kolmogorov-Smirnov test. Results: In the normal BMI group, there were 13 male patients and 27 female patients, with a mean follow-up duration of 26.15 ± 13.16 months. The mean age in this group was 21.93 ± 7.94 years. The elevated BMI group consisted of 12 male patients and 18 female patients, with a mean follow-up duration of 27.50 ± 15.79 months and a mean age of 23.30 ± 8.43 years. At the final follow-up, the incidence of surgical failure (patellar redislocation or subluxation and necessitating secondary surgery) was significantly higher in the elevated BMI group (6 out of 30 patients; 20.0%) compared with the normal BMI group (1 out of 40 patients; 2.5%) (P < .05). Both groups demonstrated significant improvement in postoperative Lysholm, IKDC, Tegner, and Kujala scores compared with the preoperative period (P < .05). Notably, the normal BMI group had significantly higher preoperative Lysholm and Tegner scores compared with the elevated BMI group (P < .05). Furthermore, the elevated BMI group exhibited less improvement in Tegner and Kujala scores compared with the normal BMI group (P < .05). Postoperative radiological parameters in both groups returned to the normal range (P < .05). There were no statistically significant differences between the 2 groups in terms of radiological parameters and their corresponding differences. Conclusion: Our study demonstrated statistically significant increases in postoperative clinical scores for both groups, although the intergroup differences varied. Specifically, patients with elevated BMI demonstrated poorer preoperative Lysholm and Tegner scores. The postoperative improvement in radiological parameters was equally good between the 2 groups.

[Research progress on femoral attachment positioning during medial patellofemoral ligament reconstruction].

Objective: To review research progress on femoral attachment positioning during medial patellofemoral ligament (MPFL) reconstruction, so as to provide a reference for accurate positioning in clinic. Methods: The literature at home and abroad on femoral attachment positioning during MPFL reconstruction was extensively reviewed and summarized. Results: MPFL is the main ligament that restricts patellar outward migration, so MPFL reconstruction is the main treatment for patellar dislocation, but the accuracy of intraoperative femoral attachment positioning will significantly affect the effectiveness. At present, there are three main methods for femoral attachment positioning in MPFL reconstruction, including imaging positioning, bony landmark positioning, and new technology. Among them, the main imaging positioning method is the "Schöttle point" method, but it has high requirements for fluoroscopic positioning, and can only be accurately positioned under standard lateral fluoroscopy of the femur. The bony landmark positioning method mainly locates the femoral attachment by touching or dissecting the bony landmarks such as adductor tubercles and medial epicondyle of femur, but its disadvantages are that the positioning is not accurate enough, the intraoperative visual field exposure requirements are high, and a large incision is required. In order to avoid the problem that the simple bony landmark positioning method, in recent years, the combination of bony landmarks combined with arthroscopy, three-dimensional (3D) printing technology, and robot-assisted positioning methods have begun to be used in clinical practice. New technology localization methods have shown good results by preparing guides before operation, planning positioning paths in advance, or directly using robots to assist positioning during operation. Conclusion: The accurate positioning of the femoral attachment in MPFL reconstruction is crucial, and the method of accurate and rapid intraoperative determination needs to be further improved and optimized. In the future, it is expected that the combination of computer image recognition correction technology and intraoperative position assistance will solve this problem.

Minimizing Redislocation Rates and Restoring Function After Patella Dislocation: A Critically Appraised Topic.

CLINICAL SCENARIO: Patella dislocation is a common knee injury resulting in decreased function, increased knee pain, and a higher risk of recurrent patella dislocation. Patients with patella instability are treated surgically or conservatively with physical therapy to minimize redislocation risk and restore function. CLINICAL QUESTION: In individuals with a patella dislocation, how does treatment (conservative therapy versus medial patellofemoral ligament [MPFL] surgery) affect redislocation rates and patient-perceived function? SUMMARY OF KEY FINDINGS: This critically appraised topic included 3 studies assessing outcomes in individuals with patella instability treated with MPFL surgery or conservative management. Outcomes included comparing redislocation rates and Kujala scale perceived knee function between participant groups. Surgery included MPFL reconstruction (MPFL-R) in 1 randomized controlled trial and 1 prospective controlled trial and MPFL repair in another randomized controlled trial. Conservative treatment included physical therapy and bracing. All 3 studies demonstrated significantly lower redislocation rates in individuals managed with surgery versus conservative treatment. Reported knee function was significantly higher in the MPFL-R group compared with individuals conservatively managed at 2-year follow-up but not at 1 year. No significant difference in knee function was present between individuals receiving MPFL repair or conservative management at a 2-year follow-up. CLINICAL BOTTOM LINE: There is moderate-level evidence to support a significant decrease in patella redislocation rates in individuals managed with MPFL surgery compared with conservative treatment. The reviewed studies suggest a significant improvement in patient-perceived knee function at 2 years following MPFL-R but no difference at 1 year following MPFL-R or 2 years after MPFL repair. Strength of Recommendations: Grade B evidence supports lower patella redislocation rates with MPFL surgery compared with nonsurgical treatment. Furthermore, this evidence suggests a potential benefit in perceived knee function 2 years after MPFL-R compared with conservative management.

Results of medial patellofemoral ligament reconstruction with and without tibial tubercle osteotomy in patellar instability: a systematic review and single-arm meta-analysis.

PURPOSE: To confirm which method provides lower rate of recurrent instability and superior clinical outcomes. METHOD: We searched PubMed, Embase and Web of Science for the trials involving one intervention or both for patellar instability: medial patellofemoral ligament reconstruction (MPFLR) with and without tibial tubercle osteotomy (TTO). The postoperative Kujala score, Lysholm score, Tegner scores and the rate of recurrent instability (dislocation or subluxation) were analyzed as the primary clinical outcome parameters in a random or fixed effects meta-analysis. RESULTS: In total, 43 articles met inclusion criteria after full-text review. A total of 2046 patients were analyzed. The overall mean age was 20.3 years (range, 9.5-60.0 years), with a mean follow-up time of 3.2 years (range, 1-8 years). The mean Kujala scores in MPFLR and MPFLR + TTO were 89.04 and 84.44, respectively. There was significant difference in Kujala scores between MPFLR and MPFLR + TTO (MD = 4.60, 95%CI: 1.07-8.13; P = 0.01). The mean Lysholm scores in MPFLR and MPFLR + TTO were 90.59 and 88.14, respectively. There was no significant difference in Lysholm scores between MPFLR and MPFLR + TTO (MD = 2.45, 95%CI: -3.20-8.10; P = 0.40). The mean Tegner scores in MPFLR and MPFLR + TTO were 5.30 and 4.88, respectively. There was no significant difference in Tegner scores between MPFLR and MPFLR + TTO (MD = 0.42, 95%CI: -0.39-1.23; P = 0.31). At final follow-up, the rates of recurrent instability in MPFLR and MPFLR + TTO were 3% and 4%, respectively. There was no significant difference in the rates between MPFLR and MPFLR + TTO (OR = 0.99, 95%CI: 0.96-1.02; P = 0.4848). CONCLUSION: MPFLR and MPFLR + TTO are effective and reliable treatments in the setting of patellofemoral instability. MPFLR seems to show a better performance in functional outcomes than MPFLR + TTO. Moreover, their rates of recurrent instability are very low, and no significant difference exists.

Arthroscopic-assisted medial retinacular plication through stab wounds using an 18-gauge needle for acute lateral patellar dislocation: Technical note.

In lateral patellar dislocation, injuries commonly involve the medial retinaculum and the medial patellofemoral ligament (MPFL). Stabilizing the medial soft tissue is crucial, with options including MPFL repair, reconstruction, or medial retinacular plication. For acute cases, MPFL reconstruction may be overly invasive, leading to donor site morbidity and scarring concerns, especially in young females. The authors propose an arthroscopic-assisted medial retinacular plication technique through stab wounds for acute dislocations, offering the advantage of being less invasive with good cosmetic outcomes.

Returning to pre-injury level of sports before 9 months after medial patellofemoral ligament reconstruction increases the incidence of anterior knee pain in young patients.

PURPOSE: This study aimed to identify the risk factors for anterior knee pain (AKP) after medial patellofemoral ligament reconstruction (MPFLR). METHODS: Patients aged 15-35 years who underwent isolated MPFLR between 2012 and 2022 were included in the study. These patients were divided into two groups (AKP and control group). Patient demographics and preoperative and postoperative clinical outcomes between the two groups were assessed and compared. Univariate logistic regression analysis was performed to explore the potential risk factors associated with postoperative AKP. Subgroup analysis stratified the results based on the time to return to sports (RTS) (>9 and ≤9 months). Furthermore, Spearman correlation analysis was performed to investigate the association between Kujala score and time to RTS. RESULTS: A total of 206 patients were included (AKP, n = 59; control, n = 147). At the 2-year follow-up, patients with AKP demonstrated a shorter duration in returning to their pre-injury activity level compared to those without AKP (9.0 ± 3.6 vs. 10.3 ± 2.7 months, p < 0.05). RTS earlier than 9 months after MPFLR was the only significant risk factor associated with postoperative AKP (odds ratio, 2.13, 95% confidence interval, 1.03-4.39; p < 0.05). Further subgroup analysis revealed that patient RTS earlier than 9 months exhibited worse patient-reported outcomes in both the total cohort and control group (p < 0.05). Furthermore, among patient RTS within 9 months, a longer recovery duration before RTS strongly correlated with a higher Kujala score (R = 0.670, p < 0.001). CONCLUSIONS: Young patients who RTS at their pre-injury levels before 9 months after MPFLR have a higher incidence of postoperative AKP and poorer functional outcomes compared to those who delay their return. Specifically, within the first 9 months after MPFLR, the earlier the RTS, the more severe the AKP symptoms. Careful consideration of the timing for RTS may help reduce the incidence of postoperative AKP. LEVEL OF EVIDENCE: Level III.

Variable Guidelines for Pediatric Medial Patellofemoral Ligament Reconstruction Rehabilitation Exists Across PRiSM Member Organizations.

Medial patellofemoral ligament (MPFL) reconstruction, typically used to restore stability to the patellofemoral joint after dislocation, often requires extensive rehabilitation to address acute impairment related to surgical intervention and also underlying non-anatomical deficits that may have contributed to the index injury. Rehabilitation guidelines, including objective functional performance assessment criteria, are lacking in the literature. We sought to summarize the clinical guidelines for rehabilitation and return to activity assessment after MPFL reconstruction as advocated by the member organizations of the Pediatric Research in Sports Medicine (PRiSM) Patellofemoral Research Interest Group (PF-RIG). We obtained and reviewed MPFL rehabilitation guidelines from 11 member organizations of the PRiSM PF-RIG, extracting information on weight-bearing advancement, bracing, use of supplemental strengthening modalities, and any objective criteria for advancing rehabilitation phases. We found highly variable agreement among guideline parameters at each treatment stage, with time-based criteria most widely used for early progression. Although functional metrics like strength or movement tests were more widely used in later phases of rehabilitation, there was substantial variation in testing mode and level of acceptable performance. Our review found that significant variability exists in current practice among PRiSM and PF-RIG member institutions regarding rehabilitation standards after MPFL reconstruction. Although we found broad consensus that objective strength or performance criteria should be employed to establish a better framework for clinical decision-making, most current guidelines lack standardization and sufficient detail to guide ideal clinical practice.

Readability and Reliability of Online Information Regarding Patellar Instability.

BACKGROUND: Assessment of readability and reliability of online resources for orthopedic patients is an area of growing interest, but there is currently limited reporting on this topic for patellar instability (PI) and medial patellofemoral ligament reconstruction (MPFLR). METHODS: Utilizing the Searchresponse.io dataset, we analyzed inquiries related to PI and MPFLR. Readability and reliability were assessed using the Automated Reading Index, Flesch Reading Ease, and the JAMA benchmark criteria. RESULTS: Analysis of 363 frequently asked questions from 130 unique websites revealed a predominant interest in fact-based information. Readability assessments indicated that the average grade level of the resources was significantly higher than the 6th grade level and reliability varied between resources. CONCLUSION: Although the internet is an easily accessible resource, we demonstrate that PI and MPFLR resources are written at a significantly higher reading level than is recommended, and there is inconsistent reliability amongst resources with medical practice websites demonstrating the lowest reliability.

Implications for Femoral Tunnel Placement in Medial Patellofemoral Ligament Reconstruction Considering the Sagittal Trochlear Groove Curvature in Severe Trochlear Dysplasia Before and After Deepening Trochleoplasty.

BACKGROUND: Medial patellofemoral ligament reconstruction (MPFL-R) aims to restore proper ligament function with minimal changes in length during range of motion, yet the ideal area for femoral fixation of the graft remains controversial. PURPOSE: To determine the region where the isometric circular path of a simulated MPFL graft (best-fit circle) follows the sagittal radius curvature of the trochlea in normal (nontrochlear dysplastic) knees and to evaluate the best-fit circle coverage of different femoral fixation points in knees with severe trochlear dysplasia (TD) and after deepening trochleoplasty. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve patients (4 male, 8 female; mean age, 24 ± 8 years) who underwent surgical treatment for recurrent lateral patellar instability due to severe TD were prospectively enrolled in this study. Four previously defined reference points for the femoral MPFL-R (Schöttle, Fujino, Stephen, and Oka) were identified, and the best-fit circle was drawn along the sagittal trochlear groove curvature. The divergence between each best-fit circle and the trochlear groove was calculated, with negative values indicating relative slackening and positive values indicating relative tightening of the simulated MPFL graft. Measurements were made on true-lateral fluoroscopic images before and after deepening trochleoplasty and compared with those of a sex-matched control group. RESULTS: The best-fit circle of the Schöttle point followed the sagittal curvature of the trochlea most closely in both the control and trochlear dysplastic knees, followed by the Fujino, Stephen, and Oka points. As the radius of the trochlear groove curvature increased, the divergence of all best-fit circles to the trochlear groove became negative (all P < .05). This effect was most pronounced at the Stephen and Oka points, followed by the Fujino and Schöttle points (all P < .05). After deepening trochleoplasty, the divergence of the Schöttle point changed toward positive values (11.6% at 40°; P < .001). Concurrently, the best-fit circle divergence of all other reference points improved toward baseline (all P < .05). CONCLUSION: The isometric circle of the Schöttle point provides the best congruence with the sagittal trochlear groove curvature in both the normal trochlea and the dysplastic trochlea. After trochleoplasty, the best-fit circles of more distal femoral fixation points resulted in better congruence with the deepened trochlear groove, whereas the best-fit circle of Schöttle indicated graft tension during flexion. CLINICAL RELEVANCE: According to the present study, different femoral fixation points should be considered depending on whether the TD is corrected.

Preoperative subjective assessment of disease-specific quality of life significantly influenced the likelihood of achieving the minimal clinically important difference after surgical stabilization for recurrent lateral patellar instability.

PURPOSE: To evaluate which factors exert a predictive value for not reaching the minimal clinically important difference (MCID) in patients who underwent a tailored operative treatment for recurrent lateral patellar dislocation (RLPD). METHODS: A total of 237 patients (male/female 71/166; 22.4 ± 6.8 years) were included. The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and subjective rating of knee function and pain (numeric analogue scale [NAS]; 0-10) were used to evaluate patients' outcomes from pre- to postoperatively. Gender, age at the time of surgery, body mass index (BMI), nicotine abuse, psychiatric diseases, cartilage status and pathoanatomic risk factors were evaluated as potential predictors for achieving the MCID using univariate logistic regression analysis. RESULTS: The MCID for the BPII 2.0 was calculated at 9.5 points. Although the BPII 2.0 and NAS for knee function and pain improved significantly in the total cohort from pre- to postoperatively (all p < 0.001), 29 patients did not reach the MCID at the final follow-up. The analysis yielded that only the preoperative NAS for function and BPII 2.0 score values were significant predictors for reaching the MCID postoperatively. The optimal threshold was calculated at 7 (NAS function) and 65.2 points (BPII 2.0). Age at the time of surgery should be considered for patients with a preoperative BPII 2.0 score >62.5. CONCLUSION: The probability of reaching BPII 2.0 MCID postoperatively depends only on the preoperative BPII 2.0 value and subjective rating of knee function, as well as age at the time of surgery for patients undergoing surgical treatment of RLPD. Here, presented results can assist clinicians in advising and presenting patients with potential outcomes following treatment for this often complex and multifactorial pathology. LEVEL OF EVIDENCE: Level III.

Lateral to medial fluoroscopic view improves the accuracy of identifying the MPFL femoral footprint using Schottle's technique.

PURPOSE: This study investigated the effect of different fluoroscopy settings on the accuracy of locating Schottle's point during medial patellofemoral ligament (MPFL) reconstruction. METHODS: The centre of the MPFL femoral footprint was identified and marked on 44 dry femurs. Two standard true lateral knee fluoroscopic images were obtained: (1) medial to lateral (ML) and (2) lateral to medial (LM). The deviation between the anatomically determined MPFL femoral footprint and the fluoroscopically identified point was measured on both fluoroscopic images. An 'acceptable tunnel location' was defined as within a 5- or 7-mm margin of error from the anatomic MPFL footprint. Distal femoral morphometric dimensions were also measured using digital calipers. Statistical analysis determined discrepancies between techniques and their relation to femoral morphometry. RESULTS: The LM view yielded a significantly smaller distance between the anatomical MPFL footprint and Schottle's point compared to the ML view (3.2 ± 1.5 vs. 4.5 ± 2.1 mm, p < 0.001). The LM view achieved acceptable tunnel locations, meeting the 5-mm error criterion in 90.9% of cases, while the ML view achieved 65.9% (p < 0.001). Both views yielded acceptable tunnel locations at similar rates using the 7-mm error criterion (n.s.). The anatomic MPFL footprint was displaced towards the anterior and proximal location in the ML view in reference to the Schottle point. No correlation was observed between any of the morphometric measurements and the deviations. CONCLUSIONS: This study demonstrated that using the LM fluoroscopic view improves the accuracy of femoral tunnel placement when identifying the MPFL footprint via the Schottle technique. Adopting the LM view in surgical practice will help surgeons locate the anatomical femoral footprint accurately, replicating the native MPFL and enhancing clinical outcomes. LEVEL OF EVIDENCE: Level 4, cadaveric study.

Arthroscopic medial patellofemoral ligament reconstruction with polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients with a follow-up of at least 2 years.

PURPOSE: The purpose of this study was to propose a surgical technique for arthroscopic medial patellofemoral ligament (MPFL) reconstruction with polyethylene suture combined with medial retinaculum plication and to evaluate the efficacy of this surgical technique in the treatment of acute patellar dislocation. METHODS: Clinical data of patients with acute patellar dislocations treated with arthroscopic MPFL reconstruction with polyethylene tape (FiberTape) combined with medial support band compression were analyzed retrospectively from January 2018 to January 2021. The mean age of the patients was 25.15 ± 4.66 years; the mean follow-up time was 27.5 (24-36) months. Clinical evaluation consisted of apprehension test results, patellar extrapolation test results, Lysholm score, Kujala score, and IKDC score, the Patellar lateral shift distance and patellar tilt angle (PTA) measured by CT scan. RESULTS: All patients had no recurrent patellar dislocation or subluxation after surgery, and the apprehension test was negative. In all patients, the Kujala score (36.0 ± 9.9 vs. 98.2 ± 3.1), the IKDC score (48.6 ± 7.0 vs. 90.6 ± 4.4) and the Lysholm score (32.8 ± 10.4 vs. 96.7 ± 3.1) had improved at the 24-month follow up (P < 0.05). In addition, PTA was significantly lower at the 12-month follow-up and 24-giving-month follow-up compared to the preoperative period (P < 0.05, Table 2). The patellar lateral shift distance decreased from 14.94 ± 6.11 mm preoperatively to 3.00 ± 1.40 mm (12-month follow up) and 3.26 ± 1.37 mm (24-month follow up), respectively. CONCLUSION: Arthroscopic MPFL reconstruction with polyethylene suture combined with medial retinaculum plication is a safe and reliable surgical technique for the treatment of acute patellar dislocation in young and middle-aged patients. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Biomechanical Properties and Kinematics of Medial Patellofemoral Ligament Reconstruction: A Systematic Review.

Background: While the biomechanical properties of the native medial patellofemoral ligament (MPFL) have been well studied, there is no comprehensive summary of the biomechanics of MPFL reconstruction (MPFLR). An accurate understanding of the kinematic properties and functional behavior of current techniques used in MPFLR is imperative to restoring native biomechanics and improving outcomes. Purpose: To provide a comprehensive review of the biomechanical effects of variations in MPFLR, specifically to determine the effect of graft choice and reconstruction technique. Study Design: Systematic review. Methods: A systematic review was performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A total of 32 studies met inclusion criteria: (1) using ≥8 human cadaveric specimens, (2) reporting on a component of MPFLR, and (3) having multiple comparison groups. Results: Gracilis, semitendinosus, and quadriceps grafts demonstrated an ultimate load to failure (N) of 206.2, 102.8, and 190.0 to 205.0 and stiffness (N/mm) of 20.4, 8.5, and 21.4 to 33.6, respectively. Single-bundle and double-bundle techniques produced an ultimate load to failure (N) of 171 and 213 and stiffness (N/mm) of 13.9 and 17.1, respectively. Anchors placed centrally and superomedially in the patella produced the smallest degree of length changes throughout range of motion in contrast to anchors placed more proximally. Sutures, suture anchors, and transosseous tunnels all produced similar ultimate load to failure, stiffness, and elongation data. Femoral tunnel malpositioning resulted in significant increases in contact pressures, patellar translation, tilt, and graft tightening or loosening. Low tension grafts (2 N) most closely restored the patellofemoral contact pressures, translation, and tilt. Graft fixation angles variably and inconsistently altered contact pressures, and patellar translation and tilt. Conclusion: Data demonstrated that placement of the MPFLR femoral tunnel at the Schöttle point is critical to success. Femoral tunnel diameter should be ≥2 mm greater than graft diameter to limit graft advancement and overtensioning. Graft fixation, regardless of graft choice or fixation angle, is optimally performed under minimal tension with patellar fixation at the medial and superomedial patella. However, lower fixation angles may reduce graft strain, and higher fixation angles may exacerbate anisometry and length changes if femoral tunnel placement is nonanatomic.

Midterm Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome.

Background: Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown. Purpose: To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes. Study Design: Case series; Level of evidence, 4. Methods: In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed. Results: The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts (P = .69). For autografts, 6 of 17 (35.3%) failures occurred with gracilis, but 0 of 13 (0%) occurred with semitendinosus (P = .02). Compared with patients without failures, patients with failed primary MPFLR were significantly younger (P = .0005) and were able to touch the palm to the floor with their knees extended (P = .03). For radiographic parameters, the patellar height and tilt were significantly higher in the failure group. The postoperative PROs were suboptimal at a mean follow-up of 5.2 years. All but 1 patient were satisfied with the final outcome. Conclusion: At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.

Incidental Finding of an Atypical Cartilaginous Tumor in an Adult Female with Recurrent Patellar Dislocation: Single-stage Extended Curettage using Freezing Nitrogen Ethanol Composite followed by Medial Patello-Femoral Ligament Reconstruction.

Atypical cartilaginous tumor (ACT) refers to a low-grade cartilaginous neoplasm microscopically identical to grade 1 chondrosarcoma, affecting the appendicular skeleton. Treatment with intralesional curettage has been found to provide sufficient local control with less morbidity compared to wide resection. This is the first reported case of a simultaneous medial patello-femoral ligament (MPFL) reconstruction with extended curettage for ACT on the ipsilateral femur. A 45-year-old female presented with chronic recurrent patellar dislocation of the right knee. Magnetic resonance imaging revealed a tear of the MPFL, with an incidental epi-metaphyseal chondroid lesion. After biopsy confirmed an ACT, single-stage extended curettage using freezing nitrogen ethanol composite (FNEC) and MPFL reconstruction was performed, followed by augmentation with bone cement and a distal femoral plate. Currently, the patient is independently ambulatory, with full range of motion about the knee. Following histologic confirmation of an ACT in the setting of a concurrent MCL tear, a single-stage procedure to address both conditions is a viable option that can reduce complications associated with multiple surgeries. Extended curettage using FNEC has been shown to produce good short-term oncologic outcomes while maximizing function.

The thickness change ratio and preservation ratio of the infrapatellar fat pad are related to anterior knee pain in patients following medial patellofemoral ligament reconstruction.

BACKGROUND: The infrapatellar fat pad (IPFP) lies extrasynovial and intracapsular, preserving the joint cavity and serving as a biochemical regulator of inflammatory reactions. However, there is a lack of research on the relationship between anterior knee pain (AKP) and the IPFP after medial patellofemoral ligament reconstruction (MPFLR). Pinpointing the source of pain enables clinicians to promptly manage and intervene, facilitating personalized rehabilitation and improving patient prognosis. METHODS: A total of 181 patients were included in the study. These patients were divided into the AKP group (n = 37) and the control group (n = 144). Clinical outcomes included three pain-related scores, Tegner activity score, patient satisfaction, etc. Imaging outcomes included the IPFP thickness, IPFP fibrosis, and the IPFP thickness change and preservation ratio. Multivariate analysis was used to determine the independent factors associated with AKP. Finally, the correlation between independent factors and three pain-related scores was analyzed to verify the results. RESULTS: The control group had better postoperative pain-related scores and Tegner activity score than the AKP group (P < 0.01). The AKP group had lower IPFP thickness change ratio and preservation ratio (P < 0.001), and smaller IPFP thickness (P < 0.05). The multivariate analysis revealed that the IPFP thickness change ratio [OR = 0.895, P < 0.001] and the IPFP preservation ratio [OR = 0.389, P < 0.001] were independent factors related to AKP, with a significant correlation between these factors and pain-related scores [|r| > 0.50, P < 0.01]. CONCLUSIONS: This study showed the lower IPFP change ratio and preservation ratio may be independent factors associated with AKP after MPFLR. Early detection and targeted intervention of the underlying pain sources can pave the way for tailored rehabilitation programs and improved surgical outcomes. LEVEL OF EVIDENCE LEVEL III.