Anatomic Medial Patellofemoral Ligament Reconstruction Research Articles

Medial Patellofemoral Ligament and Lateral Patellofemoral Ligament Reconstruction after Tibial Tuberosity Transposition in a Young Woman with Patellar Instability

In patients with reccurent lateral and medial patellar instability, isolated medial patellofemoral ligament (MPFL) reconstruction may be insufficient due to poor lateral retinacular tissue quality. In this report, we describe a case of a patient that underwent simultaneous MPFL and lateral patellofemoral ligament (LPFL) reconstruction on the left knee due to chronic bidirectional patellar instability. A 29-year-old female patient presented with first-time lateral patellar dislocation five years ago due to acute strain. She underwent a tibial tuberosity transposition in another hospital. After the surgery, she suffered from recurrent medial and lateral patellar dislocation and presented to our center. MPFL and concomitant LPFL reconstruction on the left knee was simultaneously performed due to bilateral patellar dislocation. The patella was stable postoperatively, and the patient underwent physiotherapy with successful results to date. Single-time patellar dislocation should be treated conservatively. Surgical treatment after the first episode of dislocation can magnitude the risk of postoperative complications. The simultaneous reconstructing of the LPFL yields patellar fixation indistinguishable from the native LPFL. These grafts provide separate tensioning depending on body anatomy, allowing for individualized stability. Anatomical MPFL reconstruction is supported by well-established high-quality research. Reconstructing the LPFL anatomically yields patellar fixation indistinguishable from the native LPFL.

Plantaris Tendon Autograft Can Restore Patellar Stability in Adolescent Medial Patellofemoral Ligament Reconstruction: A Technical Note.

Medial patellofemoral ligament reconstruction is a standard treatment option for patients with patellar instability. The main purpose of this study was to determine whether isolated anatomic medial patellofemoral ligament reconstruction using double folded, four-strand plantaris tendon autograft restores patellar stability in adolescent patients. Plantaris tendon autografts were harvested through proximal approach and used in four adolescent patients. A four-strand autograft was prepared in a double-limbed configuration and fixed on the patella and the femur with suture anchors and interference screws, respectively. The mean Kujala score improved significantly from 44 ± 24 SD (range, 19 to 69) points preoperatively to 94 ± 10 SD (range, 78 to 100) points postoperatively (P< 0.001). All patients reported excellent subjective outcomes and returned to their pre-injury level of sporting activities. The use of a four-strand plantaris tendon autograft in isolated anatomic medial patellofemoral ligament reconstruction can restore patellar stability in adolescents.

Medial Patellofemoral Ligament Reconstruction Using Allografts in Skeletally Immature Patients

Background: Patellar instability has the highest incidence in adolescents aged between 14 and 18 years. The unique relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis in skeletally immature patients warrants precisely positioned MPFL graft insertion. A paucity of data are available evaluating the results of MPFL reconstruction using allograft tendon before skeletal maturity. Purposes: (1) To assess the results of MPFL reconstruction using allograft tendon in skeletally immature patients by analyzing redislocation and reoperation rates, radiological outcomes, and patient-reported outcomes and (2) to determine whether epidemiological, intraoperative, or radiographic factors influence recurrent instability and clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: Prospectively collected data were retrospectively analyzed for 69 skeletally immature patients who experienced a first-time or recurrent lateral patellar dislocation and were treated with anatomic MPFL reconstruction. Inclusion criteria were MPFL reconstruction using allograft and the availability of preoperative magnetic resonance imaging scans in the presence of open or partially open physes. Patients with <2 years of follow-up and patients with previous surgeries on the same knee were excluded from the study. Preoperative radiographic imaging was reviewed and analyzed. Trochlear dysplasia, tibial tubercle–trochlear groove distance, and patellar height were evaluated. Descriptive data, concomitant injuries, surgical procedure details, complications, and postoperative history were assessed via review of medical records and patient charts. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively, including Kujala score, Lysholm score, and Tegner activity score. Return-to-sports rate was assessed. The influence of epidemiological, intraoperative, and radiographic parameters on the redislocation rates and clinical outcomes was assessed using a multiple linear regression model. Results: A total of 79 physeal-sparing MPFL reconstructions (69 patients) met the inclusion criteria. The mean age of the patient cohort was 14.7 ± 1.8 years (range, 8.5-16.9 years). Within the mean follow-up time of 37.9 ± 12.1 months (range, 24-85 months after surgery, there were 12 patients with clinical failures resulting in reoperation. Eleven patients experienced a redislocation of the patella, and 1 patient sustained a transverse noncontact patellar fracture 6 months after index surgery that required operative fixation. No injuries to the distal femoral physes were clinically observed. At the final follow-up, patients had a mean Lysholm score (1-100) of 96.5 ± 6.7, a mean Kujala score (1-100) of 96.5 ± 7.4, and a mean Tegner Activity Scale score (1-10) of 4.9 ± 1.3. Patellar height and trochlear dysplasia did not influence redislocation or clinical scores. In total, 57 of the 63 patients (90.5%) who were engaged in sports before injury returned to the same or higher level of competition. In a subgroup analysis of patients who underwent isolated MPFL reconstruction (n = 44) without concomitant procedures, 9 patients (20.5%) experienced failure and had a redislocation. A univariate analysis of hazards for failure based on patient-specific variables was carried out. A body mass index ≥30 conveyed a hazard ratio of 2.51 (95% CI, 0.63-10.1; P = .19), and the tibial tubercle-trochlear groove distance by increments of 1 mm was associated with a hazard ratio of 2.02 (95% CI, 0.51-8.11; P = .32). Conclusion: Physeal-sparing anatomic reconstruction of the MPFL using an allograft tendon in skeletally immature patients was a safe and effective treatment for patellar instability, regardless of patellar height and trochlear dysplasia. Failure rates decreased when the MPFL reconstruction was performed concomitantly with a tibial tubercle osteotomy.

Effectiveness of anatomical medial patellofemoral ligament reconstruction in mid-adolescent athletes with recurrent patellar dislocation and their return to sports

article: Effectiveness of anatomical medial patellofemoral ligament reconstruction in mid-adolescent athletes with recurrent patellar dislocation and their return to sports - Medicina dello Sport 2022 June;75(2):248-62 - Minerva Medica - Journals

Medial Patellofemoral Ligament Reconstruction Using Adductor-Transfer and Adductor-Sling at Nonanatomic Femoral Attachment Sites Leads to Unfavorable Graft-Length Change Patterns: A Descriptive Biomechanical Study

To compare the graft length change patterns in nonanatomic adductor-transfer (AT) and adductor-sling (AS) medial patellofemoral ligament (MPFL) reconstruction with those in anatomic MPFL reconstruction (MPFLR) and to investigate the favorable isometric ranges (FIRs) of knee flexion. Eight small fresh-frozen cadaveric knees were mounted in a knee-customized jig with tensioned muscles to measure graft length changes from two patellar points to four femoral attachments using a linear variable displacement transducer. Femoral attachments were at the MPFL footprint center (MPFL-C) in anatomic MPFLR, adductor magnus (AM) footprint center (AM-C) in AT, and at 5-mm (AM-5) or 10-mm (AM-10) points proximal to AM-C in AS. The FIRs of these femoral attachments were determined after zeroing the graft length changes at different initial fixation angles. Anatomic MPFL-C resulted in almost isometric graft length changes from 0° to 90°. At AM-C, the graft length changes displayed an increase from 0° to 45° and significantly greater length changes than those at MPFL-C from 60° to 90°. The graft length changes at both AM-5 and at AM-10 continuously increased with knee flexion angles and presented significantly larger graft length changes than those at MPFL-C and at AM-C from 30° to 90° and 60° to 90°, respectively. After zeroing graft length changes at different fixation angles, the FIRs of the MPFL-C covered all knee flexion angles, regardless of the patellar attachments and initial fixation angles. Moreover, with the smaller FIRs of AM-C observed at any fixation angle when compared with MPFL-C, fixing the graft at 0° to 30° in AT allowed the FIRs to cover the whole functional flexion range. However, the significantly larger graft length changes of both AM-5 and AM-10 resulted in extremely limited FIRs at any fixation angle. Anatomic MPFL-C resulted in a favorable graft length change range (less than 2 mm) at 0° to 90° of knee flexion, which was close to the isometric graft behavior. However, nonanatomic attachments of AM-C in AT, and both AM-5 and AM-10 in AS caused significant anisometric graft length change patterns and limited FIRs. Moreover, AT had a smaller range of graft length change but wider FIRs compared to AS, indicating superior graft behavior for MPFLR. Anatomic MPFLR is preferable for the treatment of in skeletally immature patients, followed in preference by nonanatomic AT. Nonanatomic AS should be performed cautiously.

Anatomic medial patellofemoral ligament (MPFL) reconstruction with and without tibial tuberosity osteotomy for objective patellar instability

PurposeThe aim of this study was to evaluate the clinical outcomes of patients treated with anatomic medial patellofemoral ligament (MPFL) reconstruction with and without tibial tuberosity osteotomy (TTO). Correlations between patient's age, gender, pre-injury physical activity and the achieved results were investigated as secondary endpoints.MethodsAn observational retrospective study with prospective collected data was performed. Inclusion criteria were: treatment with anatomic MPFL reconstruction with gracilis tendon according to Schӧttle’s technique performed between 2011 and 2017; associated TTO as unique accessory procedure; skeletal joint maturity; a minimum follow-up of 12 months after surgery. Clinical outcomes were assessed with the Kujala, Lysholm and Tegner scores.ResultsForty patients (42 knees) were included, 64% of them underwent TTO. The Kujala score significantly improved from 47.4 ± 17.6 preoperatively to 89.4 ± 13.6 postoperatively (p < 0.01). The average Lysholm score was 45.6 ± 20.5 preoperatively: it showed a significant increase to 89.8 ± 12.8 postoperatively (p < 0.01). Pre-injury mean Tegner was 5.9 ± 1.8, while it dropped to 3.0 ± 1.6 after injury. After surgery, Tegner resulted 4.9 ± 1.6. Forty-three percent of patients regained the pre-injury sport activity level. Redislocation rate was 2.4%.ConclusionAnatomic MPFL reconstruction allows excellent patellar stability recovery, knee functionality improvement, return to Activities of Daily Living and a low redislocation rate. Better results were achieved in younger (under 30 years old) and higher sports activity-level subjects. The TTO association provided clinical results comparable to isolated MPFL reconstructions, suggesting that the two procedures can be safely accomplished together without affecting the positive outcomes.Level of evidenceLevel IV.

Anatomic and Biomechanical Properties of Flat Medial Patellofemoral Ligament Reconstruction Using an Adductor Magnus Tendon Graft: A Human Cadaveric Study

Background: In contrast to the majority of existing techniques for reconstruction of the medial patellofemoral ligament (MPFL), the technique described in this article uses the adductor magnus muscle tendon to gain a flat, broad graft, leaving its distal femoral insertion intact, and does not require drilling within or near the femoral physis. It also allows for soft tissue patellar fixation and could facilitate anatomic MPFL reconstruction in skeletally immature patients. Purpose: To evaluate the anatomic and structural properties of the native MPFL and the adductor tendon (AT), followed by biomechanical evaluation of the proposed reconstruction. Study Design: Descriptive laboratory study. Methods: The morphological and topographical features of the AT and MPFL were evaluated in 12 fresh-frozen cadaveric knees. The distance between the distal insertion of the AT on the adductor tubercle and the adductor hiatus, as well as the desired length of the graft, was measured to evaluate this graft’s application potential. Load-to-failure tests were performed to determine the biomechanical properties of the proposed reconstruction construct. The construct was placed in a uniaxial testing machine and cyclically loaded 500 times between 5 and 50 N, followed by load to failure, to measure the maximum elongation, stiffness, and maximum load. Results: The mean ± SD length of the AT was 12.6 ± 1.5 cm, and the mean distance between the insertion on the adductor tubercle and adductor hiatus was 10.8 ± 1.3 cm, exceeding the mean desired length of the graft (7.5 ± 0.5 cm) by 3.3 ± 0.7 cm. The distal insertion of the AT was slightly proximal and posterior to the insertion of the MPFL. The maximum elongation after cyclical loading was 1.9 ± 0.4 mm. Ultimately, the mean stiffness and load to failure were 26.2 ± 7.6 N/mm and 169.7 ± 19.2 N, respectively. The AT graft failed at patellar fixation in 2 of the initially tested specimens and at the femoral insertion in the remaining 10. Conclusion: The described reconstruction using the AT has potential for MPFL reconstruction. The AT graft presents a graft of significant volume, beneficial anatomic topography, and adequate tensile properties in comparison with the native MPFL following the data from previously published studies. Clinical Relevance: Given its advantageous anatomic relationship as an application that avoids femoral drilling and osseous patellar fixation, the AT may be considered a graft for MPFL reconstruction in skeletally immature patients.

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.

Anterior and distal tunnel orientation for anatomic reconstruction of the medial patellofemoral ligament is safer in patients with open growth plates.

In patients with open growth plates, the direction of tunneling that avoids distal femoral physis (DFP) damage in anatomic reconstructions of the medial patellofemoral ligament (MPFL) has been a topic of discussion. The objective of this study was to determine the ideal orientation for anatomic reconstructions of MPFL tunneling that minimized DFP damage while avoiding breaching the intercondylar notch. Eighty magnetic resonance images of patients aged 10 through 17 were obtained, randomly sampled from the institutional database. A de novo software was developed to obtain 3D models of the distal femur and DFP. In each model, the anatomical insertion point of the MPFL was determined as defined by Stephen. A 20-mm-depth drilling was simulated, starting from the insertion point at every possible angle within a 90° cone using 5-, 6- and 7-mm drills. Physeal damage for each pair of angles and each drill size was determined. Damage was expressed as a percentage of total physis volume. Statistical analysis was conducted using Student's t test and one-way ANOVA. Maximum physeal damage (5.35% [4.47-6.24]) was obtained with the 7-mm drill when drilling 3° cephalic and 15° posterior from insertion without differences between sexes (n.s.). Minimal physeal damage (0.22% [0.07-0.37]) was obtained using the 5-mm drill aimed 45° distal and 0° anteroposterior, not affected by sex (n.s.). Considering intra-articular drilling avoidance, the safest zone was obtained when aiming 30°-40° distal and 5°-35° anterior, regardless of sex. Ideal femoral tunnel orientation, avoiding physeal damage and breaching of the intercondylar notch, was obtained when aiming 30°-40° distal and 5°-35° anterior, regardless of sex. This area is a safe zone that allows anatomic MPFL reconstruction of patients with an open physis.

Physeal-Sparing Medial Patellofemoral Ligament Reconstruction With Suture Anchor for Femoral Graft Fixation

Patellar instability is a common problem in the active pediatric population. When nonoperative treatment of the instability fails, growth-respecting surgical stabilization techniques are required. As the incidence of medial patellofemoral ligament (MPFL) reconstruction has increased, techniques have improved to avoid physeal injury to the distal femur. These techniques are technically demanding because of the small size of the distal femoral epiphysis in children, as well as the relatively large socket size (7-8 mm in diameter, >20 mm in length) required for sound fixation with a tenodesis screw as originally described. The size of the femoral tunnel for interference fixation puts the surrounding structures at risk of damage. We present a modification of the epiphyseal socket technique for anatomic growth-sparing MPFL reconstruction using a small soft anchor for femoral graft fixation. This has the proposed advantages of diminishing volumetric bony removal from the epiphysis; increasing the margin of safety with respect to notch, trochlear, and/or physeal damage; and reducing the risk of thermal damage to the physis during socket reaming. This technique is technically simple and can be easily learned by surgeons familiar with adult MPFL reconstruction techniques.

Medial Patellofemoral Ligament Reconstruction and Lateral Retinacular Lengthening in the Skeletally Immature Patient

Patellar instability remains a ubiquitous and troublesome problem in orthopaedics and represents a challenge in the pediatric population. Reconstruction of the medial patellofemoral ligament (MPFL) has become a mainstay of patellar instability management in recent years. As with any procedure at or around the physes, there is concern among surgeons regarding safe placement of hardware and drilled tunnels. The authors describe a technique for anatomic MPFL reconstruction with the aid of fluoroscopic guidance to maintain a “safe zone” without violating the distal femoral physis. This technique allows for reliable MPFL reconstruction in the skeletally immature population with concomitant lateral lengthening, while requiring only minor deviations from the procedure in a skeletally mature patient.

Anatomical double-bundle medial patellofemoral ligament reconstruction in recurrent patellar dislocation using autologous gracilis tendon graft

Background Recurrent lateral instability of the patella after traumatic patellar dislocation always involves injury to the medial patellar soft tissue restraints. The purpose of the study was to assess the results of double-bundle medial patellofemoral ligament (MPFL) reconstruction in the management of recurrent lateral patellar dislocations. Patients and methods Between January 2012 and November 2014, MPFL reconstruction was performed in 25 knees in 19 patients (12 females and seven males) at Benha University Hospital. The inclusion criteria included patients with recurrent dislocations of the patella (more than two times) with deficient medial retinacula. Autogenous gracilis graft was used as double bundle. Graft was fixed at the femoral side using interference screws and at the patellar side using incomplete tunnels and bone groove in the medial half of the patella. Results Average follow-up period was 32.16±5.8 months. At the final follow-up, average postoperative Lysholm score improved significantly from 58.88±5.87 to 90.68±2.77 (P Conclusion Anatomical double-bundle MPFL reconstruction is a simple and cheap technique used in the current case series that provides accurate femoral and patellar anatomical insertion points at the insertion sites and allows proper tensioning of the graft maintaining normal patellar glide, with overall favorable outcome results.

Medial patellofemoral ligament double-bundle reconstruction using a double L-shaped medial patellar tunnel

Patellar instability is a common clinical problem encountered in orthopaedics. Double-bundle medial patellofemoral ligament (MPFL) reconstruction has become the most popular technique in MPFL reconstructions. However, the optimal method for graft fixation onto the patella remains controversial. In this article, we propose a new technique for double-bundle MPFL reconstruction using a custom-designed instrument. By using a Swan sagittal aimer to drill sagittal tunnels, two L-shaped tunnels are created. Double-bundle reconstruction is then performed. This technique makes the procedure more controllable, while retaining characteristics of an anatomic double-bundle MPFL reconstruction. We believe the technique of MPFL double-bundle reconstruction using a double L-shaped medial patellar tunnel is a new approach that is able to achieve stable and satisfactory results.

The Medial Patellofemoral Ligament Is a Dynamic and Anisometric Structure: An In Vivo Study on Length Changes and Isometry

Background: Medial patellofemoral ligament (MPFL) reconstruction is associated with a high rate of complications, including recurrent instability and persistent knee pain. Technical errors are among the primary causes of these complications. Understanding the effect of adjusting patellofemoral attachments on length change patterns may help surgeons to optimize graft placement during MPFL reconstruction and to reduce graft failure rates. Purpose: To determine the in vivo length changes of the MPFL during dynamic, weightbearing motion and to map the isometry of the 3-dimensional wrapping paths from various attachments on the medial femoral epicondyle to the patella. Study Design: Descriptive laboratory study. Methods: Fifteen healthy participants were studied with a combined computed tomography and biplane fluoroscopic imaging technique during a lunge motion (full extension to ~110° of flexion). On the medial femoral epicondyle, 185 attachments were projected, including the anatomic MPFL footprint, which was divided into 5 attachments (central, proximal, distal, posterior, and anterior). The patellar MPFL area was divided into 3 possible attachments (proximal, central, and distal). The length changes of the shortest 3-dimensional wrapping paths of the various patellofemoral combinations were subsequently measured and mapped. Results: For the 3 patellar attachments, the most isometric attachment, with an approximate 4% length change, was located posterior and proximal to the anatomic femoral MPFL attachment, close to the adductor tubercle. Attachments proximal and anterior to the isometric area resulted in increasing lengths with increasing knee flexion, whereas distal and posterior attachments caused decreasing lengths with increasing knee flexion. The anatomic MPFL was tightest in extension, decreased in length until approximately 30° of flexion, and then stayed near isometric for the remainder of the motion. Changing both the femoral and patellar attachments significantly affected the length changes of the anatomic MPFL (P < .001 for both). Conclusion: The most isometric location for MPFL reconstruction was posterior and proximal to the anatomic femoral MPFL attachment. The anatomic MPFL is a dynamic, anisometric structure that was tight in extension and early flexion and near isometric beyond 30° of flexion. Clinical Relevance: Proximal and anterior MPFL tunnel positioning should be avoided, and the importance of anatomic MPFL reconstruction is underscored with the results found in this study.

A Simple Method of Measuring the Distance From the Schöttle Point to the Medial Distal Femoral Physis With MRI.

Background:Medial patellofemoral ligament (MPFL) reconstruction is the treatment of choice for recurrent patellar instability in the skeletally immature patient. Avoiding the open physes during anatomic MPFL reconstruction is a challenge in this population.Purpose:To describe a novel method using magnetic resonance imaging (MRI) to determine the distance from the Schöttle point to the medial distal femoral physis among skeletally immature individuals with patellar instability.Study Design:Descriptive laboratory study.Methods:Preoperative MRI scans were analyzed from 34 patients with open distal femoral physes and lateral patellar instability. With the multiplanar reconstruction mode on a picture archiving and communication system (PACS), the location of the Schöttle point was determined according to previously reported distances from the posterior femoral cortical line and the posterior origin of the medial femoral condyle. This location was then extrapolated to the most medial sagittal slice on MRI showing the medial distal femoral physis. The distance was measured from this point to the most distal aspect of the physis.Results:The mean age of the study cohort was 13.6 years (range, 10.6-15.7 years); there were 13 males and 21 females. The mean distance from the medial distal femoral physis to the Schöttle point was 7.27 ± 1.78 mm. The Schöttle point was distal to the medial distal femoral physis in all cases. There was no significant correlation between age and mean distance in either the overall study population (r = 0.046, P = .798) or when stratified by sex (females, P = .629; males, P = .089). The distance between the Schöttle point and the medial distal femoral physis was shorter for females than for males (6.51 vs 7.71 mm, P = .043). After adjustment for age, females on average were 1.31 mm closer to the Schöttle point than were males (B = –1.31, P = .041).Conclusion:This technique can be used to determine the distance between the medial distal femoral physis and the Schöttle point. The Schöttle point was distal to the physis in all patients, and it was closer to the physis in skeletally immature females compared with age-matched males.Clinical Relevance:The long-term repercussions of improperly placed MPFL reconstruction include recurrent patellar instability, increased patellofemoral contact pressures and overtensioning of the ligament, and possibly patellofemoral arthritis. The current technique can be used preoperatively to determine the appropriate safe distance for drilling a socket distal to the physis.

Anatomic Medial Patellofemoral Ligament Reconstruction Without Bone Tunnels or Anchors in the Patella

Medial patellofemoral ligament reconstruction is an essential component of surgical treatment for recurrent dislocation of the patella. Various techniques have been described, most of which potentially increase the risk of patellar fracture. We present a new technique for anatomic medial patellofemoral ligament reconstruction without using suture anchors or patellar tunnels, therefore, eliminating the risk of iatrogenic patellar fracture and making a revision procedure easier in case of failure.

Anatomic Double-Bundle Medial Patellofemoral Ligament Reconstruction with Autologous Semitendinosus: Aperture Fixation Both at the Femur and the Patella.

Medial patellofemoral ligament (MPFL) represents the main restraint against lateral patellar displacement. The MPFL insertion at the patella is up to 30 mm wide and is located along the upper half of the medial patellar rim. The femoral insertion of the MPFL is approximately 10 mm distal to the apex of the adductor tubercle and 16 mm proximal to the medial epicondyle. Since most of the patients suffer from MPFL rupture just after the first patellar dislocation, MPFL reconstruction results necessarily in all cases of chronic objective patellar instability to reestablish the primary passive patellofemoral stabilizer. Over time, different techniques of MPFL reconstruction have been proposed with promising results in terms of patient satisfaction and redislocation rate. However, each of these techniques may present peculiar problems and/or complications. An anatomic double-bundle MPFL reconstruction through an aperture fixation both at the femur and at the patella is here presented. The anatomic double-bundle MPFL reconstruction could allow recreating the fan-shape and biomechanics of original MPFL, whereas aperture fixation could provide a strong and safe fixation without risk of loosening or slackening of the graft.

Double-bundle anatomical medial patellofemoral ligament reconstruction with lateral retinaculum plasty can lead to good outcomes in patients with patellar dislocation.

To evaluate the clinical outcomes of double-bundle anatomical medial patellofemoral ligament (MPFL) reconstruction combined with lateral retinaculum plasty versus isolated MPFL reconstruction for patellar dislocation. From 2011 to 2013, 64 patients underwent either double-bundle anatomical MPFL reconstruction combined with lateral retinaculum plasty (Group A, 32 patients), or isolated MPFL reconstruction (Group B, 32 patients). Clinical evaluations were performed 2years post-operatively and included determination of the number of patients with patellar redislocation, the patellar tilt angle, lateral patellar shift, subjective symptoms, and functional outcomes as evaluated with the Kujala score and Lysholm score. No dislocation or subluxation occurred during the 25-month follow-up. Radiographically, the patellar tilt angle was 6.0°±1.7° in Group A and 6.7°±2.0° in Group B, without a significant difference (n. s). The lateral patellar shift was 8.0±2.6mm in Group A and 8.5±2.4mm in Group B (n. s). The mean Kujala score was 91.8±3.7 in Group A and 91.5±3.6 in Group B post-operatively (n. s), and the mean Lysholm score was 92.5±3.8 and 90.8±4.9, respectively (n. s). Double-bundle anatomical MPFL reconstruction with lateral retinaculum plasty is a promising procedure that provides a new option for patellar dislocation. III.

Treatment of patellofemoral instability in adolescent by anatomical double-bundle medial patellofemoral ligament reconstruction with double suture anchor technique

To explore the clinical outcomes of anatomical double-bundle medial patellofemoral ligament (MPFL) reconstruction with double suture anchor technique in treating patellofemoral instability in adolescent. Methods: Twenty-five young people with patellofemoral instability (25 knees) in our department from January 2013 to December 2014 were enrolled for this study. All patients were performed anatomical double-bundle MPFL reconstruction with arthroscopic-assisted suture anchors technique in the patella, and fixed in the femoral socket with absorbable interference screw. All patients are evaluated by different methods, including patient's satisfaction, patellar apprehension test, recurrent subluxation/dislocation, CT assessment of bone tunnel and patellar tilt angle. Lysholm scores, Tegner scores and Kujala scores were recorded at the final follow-up. Results: The mean follow-up was 24 (range 20-40) months. All cases were observed in negative patellar apprehension test. Infection, recurrent subluxation/dislocation and patellar fracture were not found at the last follow-up. CT results demonstrated that the tunnel position were good. The patellar tilt angle was decreased from 21.6°±2.3° to 10.5°±1.6° (P<0.05); the Lysholm scores was increased from 51.7±5.3 to 93.8±6.5 (P<0.05). Tegner scores was increased from 4.1±1.1 to 5.5±0.6 (P<0.05). Kujala scores was increased from 53.5±6.4 to 94.6±4.3 (P<0.05). Conclusion: Arthroscopic-assisted anatomical double-bundle MPFL reconstruction with the suture anchors technique is a safe, minimal invasive and effective surgical option for treating patellofemoral instability in adolescent.

Length change patterns and shape of a grafted tendon after anatomical medial patellofemoral ligament reconstruction differs from that in a healthy knee

Recurrent patellar dislocation is currently treated with anatomical reconstruction of the medial patellofemoral ligament (MPFL), and favourable postoperative outcomes have been reported. However, it is uncertain if healthy MPFL function is restored by anatomical reconstruction. The hypothesis in this study was that stabilization of the patella following MPFL reconstruction would be improved compared with that before surgery, but that function of the grafted tendon would differ from that of a healthy MPFL. The objective was to analyse the length change patterns of the MPFL before surgery and the grafted tendon after surgery in patients with recurrent patellar dislocation treated with anatomical MPFL reconstruction. The subjects were 12 patients (13 knees) in whom recurrent patellar dislocation was treated with anatomical MPFL reconstruction. The length change patterns of the MPFL and reconstructed ligament were analysed at extension and flexion of the knee joint using open MRI. The postoperative grafted tendon length was significantly shorter than that of the preoperative MPFL at knee extension, and significantly longer at 90° and 120° of knee flexion. The postoperative length of the grafted tendon only changed slightly from 0° to 30° of knee flexion, and then significantly decreased at flexion of 30° or more. The morphology of the grafted tendon was linear until 60° knee flexion, but became convex toward the extraarticular side at flexion of 90° or more. The grafted tendon length at knee extension was shorter than that of the preoperative MPFL, but there was no significant difference at 30° flexion. These findings suggest that the effect of damping of the patella with a grafted tendon after MPFL reconstruction may differ from that in a healthy knee. In addition, the morphology at 60° knee flexion was improved to linear after surgery, suggesting that ligament morphology at this flexion was normalized by MPFL reconstruction. III.