Technique For Medial Patellofemoral Ligament Reconstruction Research Articles

Treatment of chronic instability of the patella by ligamentoplasty of the medial patellofemoral ligament

Objective and potential Patellofemoral Instability (PFI) is linked to different anatomical anomalies. It has been suggested that in the majority of cases of patellar dislocation, the Medial Patellofemoral Ligament (MPFL) is ruptured with a high recurrence rate, particularly in female patients. Although MPFL tear is not the primary cause of instability, MPFL reconstruction is effective in stabilizing the knee and can single-handedly prevent lateral patellar dislocation. There is limited but growing evidence that MPFL reconstruction for patellofemoral instability leads to excellent functional outcomes. In this work, we report our technique of MPFL reconstruction using the gracilis tendon with a review of recent literature concerning MPFL reconstruction and functional results in the face of objective patellar instabilities treated solely by MPFL reconstruction.

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.

Length Changes of the Medial Patellofemoral Ligament During In Vivo Knee Motion: An Evaluation Using Dynamic Computed Tomography

Background: Medial patellofemoral ligament (MPFL) reconstruction is associated with high complication rates because of graft overloading from incorrect graft positioning. To improve clinical outcomes, it is crucial to gain a better understanding of MPFL elongation patterns. Purpose: To assess MPFL length changes in healthy knees from 0° to 90° of dynamic flexion and their relationship with anatomic parameters of the patellofemoral joint. Study Design: Descriptive laboratory study. Methods: Dynamic computed tomography scans of an active flexion-extension-flexion movement in 115 knees from 63 healthy participants were evaluated to construct knee joint models. Using these models, the MPFL length was measured as the shortest wrapping path from the Schöttle point on the femur to 3 insertion points on the superomedial border of the patella (proximal, central, and distal). MPFL length changes (%) relative to the length in full extension were calculated, and their correlations with the tibial tuberosity–trochlear groove distance, Caton-Deschamps index, and lateral trochlear inclination were analyzed. Results: The proximal fiber was the longest in full extension and progressively decreased to a median length of −6.0% at 90° of flexion. The central fiber exhibited the most isometric pattern during knee flexion, showing a median maximal decrease of 2.8% relative to the full extension length and no evident elongation. The distal fiber first slightly decreased in length but increased at deeper flexion angles. The median overall length changes were 4.6, 4.7, and 5.7 mm for the proximal, central, and distal patellar insertion, respectively. These values were either not or very weakly correlated with the tibial tuberosity–trochlear groove distance, Caton-Deschamps index, and lateral trochlear inclination when the anatomic parameters were within the healthy range. Conclusion: The median MPFL length changed by approximately 5 mm between 0° and 90° of flexion. Proximally, the length continuously decreased, indicating slackening behavior. Distally, the length increased at deeper flexion angles, indicating tightening behavior. Clinical Relevance: In MPFL reconstruction techniques utilizing the Schöttle point to establish the femoral insertion, one should avoid distal patellar insertion, as it causes elongation of the ligament, which may increase the risk for complications due to overloading.

Combining Medial Patellofemoral Ligament Reconstruction With Patellar Tendon Repair Using Biocomposite Swivel Lock Anchors: Surgical Technique and Case Report

Introduction: Injuries to the medial patellofemoral ligament (MPFL) and patellar tendon in isolation are well-documented entities. There is a paucity of literature describing this combination of injuries and treatment of this concomitant injury pattern. Objective: The intent of this manuscript was to document the combined injury pattern of a concomitant MPFL rupture and patellar tendon disruption. We also aimed to describe a treatment option for this rarely documented injury pattern. Materials and Methods: Our MPFL reconstruction technique utilized a gracilis allograft and 2 biocomposite anchors for the patella. Our patellar tendon repair utilized Ethibond suture in a Krakow stitch fashion, which was subsequently incorporated into the anchors used for the MPFL reconstruction. Results: Our patient successfully transitioned through a specific postoperative range of motion protocol by increasing knee flexion 30 degrees every 2 weeks, beginning at 0 to 30 degrees at the first postoperative visit. Our patient was able to straight leg raise by 6 weeks, began formal physical therapy at 8 weeks, and resumed all normal activity at 6 months. Conclusion: We demonstrated a novel technique to repair a combined injury of the MPFL and patellar tendon that produced good clinical outcomes through 6 months.

Arthroscopic reconstruction of the medial patellofemoral ligament in skeletally immature patients using the modified sling procedure: a novel technique for MPFL reconstruction

BackgroundPatellar dislocation is common in young people. Although isolated anatomic double-bundle reconstruction of the MPFL is a common and effective surgical treatment for patellofemoral instability, concerns about the risk of injury to the epiphysis remain.MethodsA total of 21 children and adolescents (9 males, 12 females; mean age: 10.7 years; range: 8 to 13 years) with recurrent patella dislocation or symptomatic instability following a primary dislocation were enrolled in the study. In all patients, double-bundle medial patellofemoral ligament (MPFL) reconstruction and femoral sling procedure were performed under arthroscopy, using an anterior half peroneus longus tendon (AHPLT) autograft. Functional outcomes were evaluated preoperatively and during follow-ups based on Kujala and Lysholm scores. Radiological examinations including radiographs, 3D-CT, and MRI were performed pre- and post-operatively.ResultsAmong two-year postoperative follow-up (range: 24–42 months) showed significant improvement in functional scores (p < 0.01). The Lysholm score increased from 68 (44.5) to 100 (0) and the Kujala score increased from 26 (34.5) to 100 (2) The patellar tilt angel improved significantly (p < 0.01) from 24.3° ± 10.4 preoperatively to 11.9° ± 7.0 postoperatively. MRIs performed 6- and 12-months post operation did not show any signs of dysfunction of the reconstructed MPFL or cartilage degeneration.Study designCase Series; Level of evidence, 4.ConclusionArthroscopic reconstruction of the MPFL using the modified sling procedure is an effective procedure for the treatment of patellar instability in skeletally immature patients.

A Patella-Sided Tensioning Technique for Medial Patellofemoral Ligament Reconstruction

Reconstruction of the medial patellofemoral ligament (MPFL) is a common procedure for treatment of recurrent patellofemoral instability. Over the last two decades, multiple surgical techniques for MPFL reconstruction have been described with no clear consensus on a superior reconstruction technique. Appropriate graft tensioning is one of the most important factors for a successful MPFL reconstruction. Overtensioning of the MPFL graft can lead to patellofemoral joint overload and undertensioning can lead to recurrent instability. Current literature demonstrates descriptions of MPFL reconstruction with final graft tensioning performed off of the femoral side. We describe a technique in this article for performing final graft tensioning from the patellar side, which gives the surgeon an option for intraoperative tension adjustments after evaluating patellar tracking.

Dynamic versus static medial patellofemoral ligament reconstruction technique in the treatment of recurrent patellar dislocation: a randomized clinical trial protocol

BackgroundThe redislocation rate of conservatively treated patella instability is high. One of the leading surgical strategies is medial patellofemoral ligament reconstruction. Over-tensioning is one of the most challenging complications in static medial patellofemoral ligament reconstruction as the graft used for reconstruction is isometric and the anatomical MPFL is a mostly dynamic structure. As an alternative to established static reconstruction techniques, dynamic graft techniques have been introduced for stabilizing the patella with the aim of providing a more physiological reconstruction of the medial patellofemoral ligament. To date, data on clinical outcomes are scarce and on biomechanical outcomes of the dynamic MPFL reconstruction are lacking. Here, we present the protocol of a randomized clinical trial for comparing clinical and biomechanical outcomes of dynamic versus static medial patellofemoral ligament reconstruction.MethodsThis study is a prospective, single blinded, randomized, multicenter, multimodal (clinical and biomechanical) clinical trial. Patients with recurrent patella dislocation requiring isolated MPFL reconstruction will be recruited and randomized to the dynamic or static reconstruction technique. Participants will be followed up for 2 years with a total of five follow-ups. Preoperative magnetic resonance imaging, upright radiographs, surgical reports and patient records will be evaluated, and clinical and functional outcomes will be measured. Patient-reported knee function and anterior knee pain as assessed with the Kujala score will serve as primary outcome. For biomechanical outcome, pre- and postoperative evaluations will be performed to assess isokinetic muscle strength, gait asymmetry, joint kinematics and kinetics, and timing of muscle activity.DiscussionThe results of the study will clarify whether the reported surgery success for patella stabilization via dynamic MPFL reconstruction is due to muscle contraction or to the passive tenodesis effect combined with clinical outcome measures. With this study, we will provide much needed information on knee biomechanics after dynamic versus static MPFL reconstruction to provide evidence to support orthopedic surgeons in evidence-based decision-making in their quest for surgical techniques most favorable for their patients.Trial registration The study protocol was registered at clinicaltrials.gov (NCT04849130). Registered 19 April 2021, https://clinicaltrials.gov/ct2/show/NCT04849130.

Medial Patellofemoral Ligament Reconstruction Techniques and Outcomes: a Scoping Review.

The purpose of this scoping literature review was to summarize the current evidence on techniques and outcomes following MPFL reconstruction including sources of evidence, key concepts, and gaps in the literature. A thorough electronic database search included studies published from 2016 to April 26, 2021, identified a total of 144 peer reviewed articles. Of the 144 identified clinical papers, 80 (56%) were of level IV evidence, 49 (34%) were of level III evidence, 11 (8%) were level II evidence, and 4 (3%) were level I evidence. Overall, 10,710 patients (11,466 knees) were included with 6871 (64%) female. The mean age of patients included in these studies was 23.5 years (range=5 to 59). In recent years, there has been a substantial quantity of evidence published on MPFL reconstruction from a variety of different countries and journals and of variable methodological design. Isolated MPFL reconstruction results in a decrease in patellar height postoperatively. Indications for isolated MPFL reconstruction versus concomitant procedures to address bony morphology is still incompletely defined. When failure does occur after MPFL reconstruction, femoral tunnel malposition is the most commonly cited cause. Despite several recent studies focused on optimal MPFL reconstruction techniques, there is currently no consensus on optimal graft type (most common being hamstring autografts, allografts, and recently synthetic grafts) or femoral fixation strategies, with similar results reported with each technique. Future studies should focus on optimal techniques for each patient population as well as specific indications for additional concomitant realignment procedures.

Dynamic Medial Patellofemoral Ligament Reconstruction in Patellar Instability: A Surgical Technique

Background: Patella instability with recurrent dislocations is a result of various pathologies, for example, patella alta, trochlea dysplasia or medial patellofemoral ligament (MPFL) rupture. The recurrent dislocation rate of conservatively treated chronic patellar instability is high; therefore, it is recommended to manage it surgically. This video presents a new operative approach to stabilize the patella in a dynamic MPFL reconstruction, which addresses the most common complications occurring in static reconstructions: malpositioning and overtensioning the graft. Indications: Surgical indications for the new dynamic procedure mirror the indications for static MPFL reconstruction. This is MPFL insufficiency (patella instability in the first 30° of knee flexion), which is most frequently seen in recurrent lateral patella dislocations. Moreover in very rare cases of first patella dislocation with a patellar instability severity score equal or higher than 4. Technique Description: The dynamic MPFL reconstruction consists of 3 steps: First, detaching and mobilizing the gracilis muscle at its anatomical insertion. Second, redirecting the freed gracilis muscle to its new patellar insertion. Third, reinserting the gracilis muscle at the patella. Results: The dynamic MPFL reconstruction has the advantage of lesser risk of overtensioning and malpositioning the graft. The insertion point of the MPFL surrogate is easier to locate, and the patella is dynamically stabilized through reflectory gracilis muscle contraction. Compared with the static reconstruction, only one instead of 3 holes have to be drilled and only 1 interference screw has to be placed, thus shortening the surgery time. From a theoretical biomechanical perspective, the dynamic tensioning is superior to the static procedure. The few accomplished studies published so far by Becher et al and Ostermeier et al show good or better functional results (Kujala, Lysholm, Tegner scores) with the dynamic MPFL reconstruction, yet higher evidence studies need to be performed. Conclusion: Dynamic MPFL reconstruction appears to be a simpler and more effective surgical technique for MPFL reconstruction. Because of its novelty, high evidence studies assessing long-term therapeutical outcomes are still lacking and need to be conducted in order to compare it conclusively with the static procedure.

The novel dynamic MPFL-reconstruction technique: cheaper and better?

PurposeReconstruction of the medial patellofemoral ligament (MPFL) is an established procedure to restore patellar stability. Aim of this study is to evaluate the results of a dynamic MPFL reconstruction technique in a large university hospital setting.MethodsTwo hundred and thirteen consecutive patients with 221 knees were surgically treated for recurrent lateral patellar dislocation. All patients obtained dynamic reconstruction of the MPFL with detachment of the gracilis tendon at the pes anserinus while maintaining the proximal origin at the gracilis muscle. Patellar fixation was performed by oblique transpatellar tunnel transfer. Follow-up data including Kujala and BANFF score, pain level as well as recurrent patella instability were collected at a minimum follow-up of 2 years.ResultsFollow-up could be obtained from 158 patients (71%). The mean follow-up time was 5.4 years. Mean pain level was 1.9 ± 2.0 on the VAS. Mean Kujala score was 78.4 ± 15.5. Mean BANFF score was 62.4 ± 22.3. MPFL-reconstructions that were performed by surgeons with a routine of more than ten procedures had a significantly shorter surgical time 52.3 ± 17.6 min. Male patients yielded higher satisfaction rates and better clinical scores compared to females. Complications occurred in 27.2% of procedures, 20.9% requiring revision surgery of which were 9.5% related to recurrent patellar instability. 78% of all patients indicated they would undergo the procedure again.ConclusionDynamic MPFL reconstruction presents a reproducible procedure with increased complication rates, inferior to the results of static reconstruction described in the literature. Despite, it appears to be an efficient procedure to restore patellar stability in a large university hospital setting, without the necessity for intraoperative fluoroscopy.Trial registrationThe study was registered in ClinicalTrials.gov with the registration number NCT04438109 on June 18th 2020.

Biomechanical comparison of two medial patellofemoral ligament reconstruction techniques: Quadriceps tendon fixation versus single-tunnel patella fixation with gracilis autograft did not differ in load to failure and stiffness

BackgroundThe purpose of this study was to evaluate the ultimate failure load and stiffness of two patellar fixation techniques for medial patellofemoral ligament (MPFL) reconstruction: (1) quadriceps tendon fixation (QT), (2) single tunnel (STG) patella fixation with gracilis autograft. MethodsA total of 16 fresh-frozen cadaveric knees (eight matched pairs) were randomized into two groups (QT vs. STG). The MPFL reconstructions were subjected to cyclic loading for 10 cycles to 30 N and then tested to failure at a constant displacement rate of 15 mm/min using a materials-testing machine (MTS 810 Universal Testing System). Failure mode, ultimate failure load and stiffness were recorded for each cadaveric specimen. ResultsThere was no significant difference in mean ultimate failure load among groups (P = 0.35). The STG group failed at a mean ultimate load of 190.04 N [standard deviation (SD) 23.18] and the QT group failed at 206.24 N (SD 37.99).The STG group had a mean stiffness of 21.38 N/mm (SD 1.44). This was not significantly higher than the mean stiffness value achieved for the QT group at 20.36 N/mm (SD 1.3) (P = 0.19). In the QT group all reconstructions failed due to tendon rupture at the patella attachment. The reason for failure in the STG group was the graft–suture connection. ConclusionsThis cadaver study showed no statistically significant difference in biomechanical performance of the evaluated patella fixation techniques, in terms of maximum load to failure and stiffness. Both techniques are reliable in terms of biomechanical properties and could offer additional surgical solutions.

Biomechanical Comparison of 2 Patellar Fixation Techniques in Medial Patellofemoral Ligament Reconstruction: Transosseous Sutures vs Suture Anchors.

Background:Multiple techniques for fixing a graft to the patella in medial patellofemoral ligament (MPFL) reconstruction have been described; however, no single technique has been shown to be superior to another.Purpose/Hypothesis:The purpose of this study was to compare the biomechanical performance of 2 different patellar fixation techniques: suture anchor (SA) and transosseous suture (TS) fixation. The hypothesis was that there would be no significant differences between the groups in ultimate failure load, stiffness, or elongation.Study Design:Controlled laboratory study.Methods:In this study, a new TS technique was biomechanically compared with the SA technique for MPFL reconstruction using 24 fresh-frozen mature porcine patellae and porcine flexor profundus tendons. The specimens were randomized into 2 groups undergoing MPFL reconstruction using either the SA technique or the TS technique (n = 12 per group). Fixation with TS was completed using 3 No. 2 UltraBraid sutures and three 2-mm transosseous tunnels. SA reconstruction was completed using 2 parallel 3.5-mm titanium SAs with 2 No. 2 UltraBraid sutures. We preconditioned each graft using a force between 5 and 20 N before cyclic loading. Then, the specimens were biomechanically tested (1000 cycles; 5-100 N; 1 Hz) and loaded under tension at 200 mm/min until failure. The ultimate failure load, stiffness, elongation, and failure mode were recorded for each specimen. The Shapiro-Wilk test and independent t tests were used to assess the data.Results:The TS technique resulted in a significantly higher mean failure load than did the SA technique (496.18 ± 93.15 vs 399.43 ± 105.35 N; P = .03). The TS technique resulted in less stiffness than did the SA technique (55.42 ± 7.92 vs 72.11 ± 10.64 N/mm; P < .01). There was no significant difference between the groups in elongation. None of the graft fixation/patellar complexes failed during cyclic testing in either group. During the load-to-failure test, the most common mode of failure in the SA group was an anchor being pulled out of the bone, whereas that in the TS group was rupture of the suture material.Conclusion:MPFL reconstruction with 3 TSs provided a higher load to failure than did the commonly used fixation method involving SAs.

A Prospective Cohort Study on Quality of Life among the Pediatric Population after Surgery for Recurrent Patellar Dislocation.

Patellofemoral instability is a frequent cause of knee pathology affecting quality of life among the pediatric population. Here, we present a prospective cohort study which included patients who had undergone surgical management using the lateral release and medial imbrication approach (LRMI) or medial patellofemoral ligament reconstruction (MPFL-R). The object of this study was to assess the quality of life among children that have undergone surgical treatment for patellar dislocation. Quality of life was assessed before and after surgery using the Pediatric International Knee Documentation Committee form (Pedi-IKDC), a questionnaire that aims to quantify knee functionality. Postoperative scarring was evaluated using The Stony Brook Scar Evaluation Scale. One hundred and eight patients were selected and grouped according to the type of procedure. Before surgery, the two groups had similar mean Pedi-IKDC scores (41,4 MPFL-R vs. 39,4 LRMI p = 0.314). Improvements were observed in the postoperative scores. The MPFL-R technique showed promising outcomes. When comparing the two surgical groups, there was a significant difference in favor of MPFL-R group (MPFL-R 77.71 points vs. LRMI 59.74 points, p < 0.0001–95% CI (11.22–24.72)). Using the Stony Brook Scar Evaluation Scale, a significant difference in scar quality in favor of MPFL-R was observed (4,5 MPFL-R vs. 2,77 LRMI p = 0.002). In conclusion, this study provides objective evidence-based outcome assessments that support the medial patellofemoral ligament reconstruction technique as the gold standard for patellofemoral instability.

Single-Incision, Single Patellar Tunnel For Double-Bundle Medial Patellofemoral Ligament Reconstruction: A Technical Note

The medial patellofemoral ligament (MPFL) is the main medial stabilizer of the patella, while reconstruction of the ligament is a common surgery performed by orthopedic surgeons. Although several surgical methods have been described regarding MPFL reconstruction, the common goals of these surgeries are to imitate the anatomic features of the native MPFL. In the single-incision and single patellar tunnel and double-bundle MPFL reconstruction technique, we will present the anatomical footprint of the MPFL located in the medial aspect of the patella, which is filled with the graft. In this technique, graft fixation is performed in the femoral tunnel using only one bioabsorbable screw without the need for fixation in the patella.

Transpatellar bone tunnels perforating the lateral or anterior cortex increase the risk of patellar fracture in MPFL reconstruction: a finite element analysis and survey of the International Patellofemoral Study Group.

(1) To determine applied patellar drilling techniques for medial patellofemoral ligament (MPFL) reconstruction among members of the International Patellofemoral Study Group (IPSG) and (2) to evaluate the risk of patellar fracture for various patellar bone tunnel locations based on a finite element analysis (FEA) model. In the first part of the study, an online survey on current MPFL reconstruction techniques was conducted among members of the IPSG. In the second part of the study, a three-dimensional FEA model of a healthy knee joint was created using a computed tomography scan. Patient-specific bone density was integrated into the patella, and cartilage of 3mm thickness was modeled for the patellofemoral joint. According to the survey's results, two different types of patellar bone tunnels (bone socket and transpatellar bone tunnel) were simulated. The risk of patellar fracture was evaluated based on the fracture risk volume (FRV) obtained from the FEA. Finite element analysis revealed that subchondral bone socket tunnel placement is associated with the lowest FRV but increased with an anterior offset (1-5mm). Transpatellar bone tunnels violating the lateral or anterior cortex showed a higher FRV compared to bone socket, with the highest values observed when the anterior cortex was penetrated. Violation of the anterior or lateral patellar cortex using transpatellar bone tunnels increased FRV compared to a subchondral patellar bone socket tunnel. In MPFL reconstruction, subchondral patellar bone socket tunnels should be considered for patellar graft fixation to avoid the risk of postoperative patellar fracture. Survey; Descriptive laboratory study/Level V.

MPFL Length Change Patterns in Asymptomatic Knees of Patients with Contralateral Patellar Instability

Objectives:Recreating the isometry of the medial patellofemoral ligament (MPFL) is critical during patellar stabilization surgery to restore patellar kinematics. The native MPFL is reported to remain constant in length from 0-70°knee flexion in normal knees. However, patients with patellar instability have morphologic abnormalities that may alter the isometric function of the ligament. Length change patterns of the intact MPFL in such patients have not been described.Methods:3D digital knee models were created from dynamic CT images of 10 patients with unilateral patellar instability who were confirmed to have no symptoms on the contralateral knee. At each flexion angle, MPFL length was calculated based on the distance between its known attachment points. Straight line representation of the MPFL was allowed to wrap around the femoral condyle to ensure accurate length measurement. Morphologic characteristics of each knee were recorded, including sulcus angle and lateral trochlear inclination (LTI) as measurements of trochlear dysplasia, trochlear alpha angle to measure trochlear length, tibial tuberosity to trochlear groove (TTTG) distance to measure malalignment, and Caton Deschamps Index (CDI) to measure patellar height. Changes in MPFL length were assessed relative to knee flexion angle in each patient and correlated with morphologic characteristics.Results:10 knees were included in this study, with a mean age of 20.4+/-4.7 yrs. Mean sulcus angle was 153.4+/-8.9°, LTI 14.1+/-4.0°, trochlear alpha angle 66.1+/-5.8°, TTTG distance 18.3+/-3.1mm, CDI 1.1+/-0.1. Mean MPFL length varied from 62.5+/-4.9mm at 50° knee flexion to 74.4+/-3.9mm at 0°, with a 20.1+/-8.8% change in length (p<0.001). No significant length changes were noted between 30° and 50° flexion. Moderate correlation was noted between increasing MPFL length change and measurements of trochlear length (R=-0.55, p=0.017).Conclusions:In the asymptomatic knees of patients with contralateral patellar instability, the calculated MPFL length based on known anatomic attachment points varied by 20.1%, or an average of 12.1mm, between 50° flexion and full extension. This suggests that the isometric function of the intact MPFL in these patients may not reflect previously described findings in anatomically normal patients. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of isometry in MPFL reconstruction techniques.

Outcomes of MPFL Reconstruction Utilizing a Quadriceps Turndown Technique in the Adolescent/Pediatric Population.

Recurrent instability following a lateral patellar dislocation is a common indication for surgical intervention. Several surgical procedures are described in the literature to address recurrent patellar instability. Medial patellofemoral ligament (MPFL) reconstruction utilizing the quadriceps turndown technique attempts to restore medial stability. Results of the quadriceps turndown technique have previously only been reported in adult populations. The purpose of this study was to assess the safety, efficacy, and patient-reported outcomes following a quadriceps turndown MPFL reconstruction in the pediatric and adolescent population. Records of all patients who underwent MPFL reconstruction using a quadriceps turndown technique between 2011 and 2018 were reviewed for demographics, risk factors, complications, mechanism of injury, and concomitant procedures. Return to activities of daily living (ADLs), return to presurgery level of sport, length of bracing, and recurrent instability were assessed with the administration of the Kujala Anterior Knee Pain Score. All analyses were completed using IBM SPSS Statistics 26. Thirty-six knees [14 female (39%), 22 male (61%)] from 34 patients met inclusion/exclusion criteria. The average follow-up length was 35.9±15.2 months. The average age was 16.3±1.8 years at the time of surgery. The average time for resumption of ADLs was 8.1±6.0 weeks after surgery. Ninety-four percent of patients returned to preinjury level of sport at an average of 23.6±12.0 weeks after surgery. Mean Kujala Anterior Knee Pain Score was 90.7±10.3. Female patients (P<0.001) reported significantly lower Kujala scores. Three patients (8%) experienced recurrent instability during ADLs and an additional 4 (11%) reported subjective feelings of instability only during sport or elevated activity. One knee required a return to the operating room for irrigation and debridement due to infection. This study demonstrates that the quadriceps turndown technique for MPFL reconstruction is a safe and effective procedure for the management of recurrent patellar instability in pediatric and adolescent patients. Level III-therapeutic.

Medial Patellofemoral Ligament Reconstruction Using a Quadriceps Tendon Autograft in a Patient with Open Physes

Recurrent patellar dislocations are correlated with an elevated risk for further patellar dislocations. Chronic patellar instability is a disabling issue for some patients and may require surgical intervention for proper treatment. Risk factors for recurrent dislocations include medial patellofemoral ligament (MPFL) tears, patella alta, trochlear dysplasia, and increased tibial tubercle to trochlear groove distance. Surgical management must be based on a patient’s unique joint pathoanatomy and typically requires medial patellofemoral ligament reconstruction, with or without accompanying procedures such as tibial tubercle osteotomy or sulcus-deepening trochleoplasty. Chronic patellar instability in minors with open growth plates, requires alternative MPFL reconstruction techniques to prevent physeal injury, because of the close proximity of the femoral physis to the MPFL insertion. This article discusses the authors’ preferred technique for surgical treatment of recurrent patellar instability with a medial patellofemoral ligament reconstruction using a quadriceps tendon autograft.

All aperture fixation technique of anatomical medial patellofemoral ligament (MPFL) reconstruction with semitendinosus double loop graft: a retrospective case series

Background: The all-aperture fixation technique for anatomical medial patellofemoral ligament (MPFL) reconstruction using a double-loop semitendinosus autograft has been proposed as a strong and biomechanically sound surgical procedure. The aim of the study was to describe the surgical procedure and report the early and mid-term results of MPFL reconstruction using patellar knotless anchors and femoral interference screws. These procedures were performed in the same institution. Methods: This is a retrospective case series studying 10 patients with chronic patellofemoral instability who underwent anatomical MPFL reconstruction by means of patellar knotless anchors and femoral interference screws. The Tegner–Lysholm score with clinical data such as apprehension test and knee range of motion (ROM) were assessed preoperatively and postoperatively. Results: After a mean follow-up of 19.4 mo, all the cases had good clinical outcomes, and none of the cases had any recurrence. The mean Lysholm score and knee ROM significantly improved from 59 and 101 preoperatively to 80.2 and 125, respectively (P&lt;0.001). Conclusions: The technique of anatomical double-bundle MPFL reconstruction by patellar knotless anchors and femoral interference screws is an effective, reproducible, and easy technique for restoring stability and function of the patellofemoral joint. Level of Evidence: Level IV.