Interference Screws Are Biomechanically Superior to Suture Anchors for Medial Patellofemoral Ligament Reconstruction: A Systematic Review and Meta-Analysis

Posterolateral Corner Reconstruction: A Systematic Review and Meta-analysis of Biomechanical Studies

BACKGROUND

Surgical reconstruction is the standard treatment for injuries to the posterolateral corner (PLC) of the knee and can be performed using either a fibular-based or combined tibiofibular-based technique. Although some comparative studies have been performed, there is no consensus regarding the reconstructive approach that confers optimal biomechanical properties of the PLC.

PURPOSE

To perform a systematic review and meta-analysis to evaluate the biomechanical properties of the knee after PLC reconstruction with fibular-based and tibiofibular-based techniques.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

A systematic review was performed by searching the PubMed, Cochrane Library, and Embase databases using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify studies that analyzed the biomechanical properties of PLC reconstruction techniques. Evaluated outcomes included varus laxity and external rotation laxity. The pooled biomechanical data were analyzed by random-effects models and heterogeneity was assessed using the I2 statistic.

RESULTS

Eleven studies met the inclusion criteria; 74 cadaveric specimens were included. Seven studies (54 specimens) evaluated the fibular-based Larson reconstruction technique, 3 studies (22 specimens) evaluated a modified fibular-based Larson reconstruction, and 1 study (7 specimens) evaluated the fibular-based Arciero reconstruction. Five studies (45 specimens) evaluated the tibiofibular-based LaPrade reconstruction technique and 2 studies (20 specimens) evaluated a modified LaPrade reconstruction. Data were pooled for fibular-based reconstructions (Larson, modified Larson, and Arciero) and tibiofibular-based reconstructions (LaPrade, modified LaPrade). Pooled analysis revealed no significant difference in varus laxity and external rotation laxity between fibular and tibiofibular reconstructions at 0°, 30°, 60°, and 90° of flexion (all P > .05).

CONCLUSION

No difference in varus laxity and external rotation laxity was observed between fibular-based and tibiofibular-based techniques for PLC reconstruction. Moreover, there was no difference in varus laxity and external rotation laxity observed between the Larson, modified Larson, and LaPrade reconstructions. These results suggest that biomechanical stability after fibular- and tibiofibular-based PLC reconstructions is similar. Further clinical investigation is warranted to validate these cadaveric findings.

Medial patellofemoral ligament reconstruction using synthetic suture tape: A systematic review of biomechanical and clinical outcomes

Purpose

To review outcomes of medial patellofemoral ligament reconstruction (MPFLR) using synthetic suture tape in biomechanical and clinical studies.

Methods

A comprehensive literature search was performed in three databases. Studies reporting biomechanical and/or clinical outcomes of MPFLR using synthetic suture tape were included. For clinical studies, the primary outcome measures included patient-reported outcomes (PROs) and adverse events.

Results

Three biomechanical studies were included. One study reported stronger integrity of fixation with suture tape versus semitendinosus autografts. One study reported similar integrity of MPFLR with knotless anchor versus soft tissue fixation. Another study found suture tape fixation between 60° and 90° of knee flexion to avoid excessive medial patellofemoral joint contact pressure after MPFLR. Eight clinical studies with 287 patients and 317 knees (36.1 % male, pooled mean age: 23.2 years old, pooled mean follow-up: 41.6 months) were included. All studies reported significant preoperative to postoperative improvement for all PROs except for the Tegner score in one study. The range of PROs were as follows (preoperative and postoperative): Lysholm (32.8-72.0 and 78.0 to 96.7), Kujala (36.0-75.2 and 78.8 to 97.7), International Knee Documentation Committee (IKDC) (48.6-69.8 and 71.3 to 91.3), and Tegner (1.0-4.6 and 4.0 to 6.5). Two studies comparing suture tape with autografts (quadriceps and gracillis tendons) reported similar postoperative PROs. The pooled rate of adverse postoperative events was 8.2 %. The pooled rate of positive patellar apprehension tests at follow-up was 3.2 %.

Conclusions

Patients undergoing MPFLR with suture tape fixation achieved significant improvements in PROs and demonstrated low rates of postoperative complications. Compared to autograft fixation, suture tape fixation provided comparable or superior clinical and biomechanical outcomes.

GelMA encapsulating BMSCs-exosomes combined with interference screw or suture anchor promotes tendon-bone healing in a rabbit model

The tendon-bone junction (TBJ), a critical transitional zone where tendons and bones connect, is particularly prone to injury due to the forces from muscle contractions and skeletal movements. Once tendon-bone injuries occur, the complex original tissue structure is difficult to restore, increasing the risk of re-tear. In this study, we initially established a rabbit model of tendon-bone injury and treated it using either interference screw or suture anchor. Biomechanical testing demonstrated the maximum tension and strength of TBJ with interference screw fixation were superior. However, histologic and immunohistochemical results showed more tissue regeneration and expression of cartilage markers at the site of injury with suture anchor fixation. Moreover, Gelatin Methacryloyl encapsulated with exosomes from mesenchymal stem cell (GelMA-exosomes) were prepared, showing a consistent and stable exosome release characteristic. The combined application of GelMA-exosomes with either interference screws or suture anchors further enhanced the healing of tendon-bone injuries, which may be achieved by promoting cellular proliferation as well as regulating the decreased expression of local pro-inflammatory factors IL-1β, IL-6 and TNF-α and increased expression of anti-inflammatory factors IL-10 and TGF-β. This provides a viable therapeutic strategy to enhance tendon-bone healing.

All-Suture Anchor Onlay Fixation for Medial Patellofemoral Ligament Reconstruction: A Biomechanical Comparison of Fixation Constructs

Background

The use of all-suture anchors (ASAs) for onlay patellar and femoral fixation of medial patellofemoral ligament (MPFL) grafts may provide clinical benefit, particularly in the small or pediatric knee; however, biomechanical data supporting the use of ASAs are lacking.

Purpose/Hypothesis

The purpose of this study was to compare ASAs to larger interference implants for MPFL reconstruction in a time-zero biomechanical model. It was hypothesized that ASAs would have comparable cyclic elongation to interference fixation and would exceed published biomechanical values for the native human MPFL.

Study Design

Controlled laboratory study.

Methods

Eighteen fresh-frozen porcine patellas and femurs were divided into equal groups (n = 9 per group) for MPFL reconstructions. Patellar fixation utilized two 3.9-mm interference suture anchors (ISAs) or two 2.6-mm ASAs, while femoral fixation utilized one 6×20-mm interference screw (IS) or one 2.6-mm ASA. Human gracilis tendon grafts were used. Specimens were dynamically loaded for 100 cycles each in sequential 5- to 30-N (phase 1) and 5- to 50-N (phase 2) blocks at 1 Hz followed by load-to-failure testing at 305 mm/min.

Results

No differences were found in cyclic elongation after phase 1 and phase 2 loading between ASA and interference implants on either the femoral or patellar side. On the femur, IS had significantly greater ultimate stiffness (54.2 vs 46.1 N/mm; P < .001) and ultimate load (366 vs 278 N; P = .019) compared to ASA. On the patella, ISAs had significantly greater ultimate stiffness (70.5 vs 53.1 N/mm; P < .001) but a significantly lower ultimate load (244 vs 307 N; P = .014) compared to ASAs. All groups significantly exceeded the published physiological values for native human MPFL stiffness and failure load.

Conclusion

ASA onlay fixation had comparable cyclic elongation to that of interference fixation for femoral and patellar MPFL reconstruction. Although differences in ultimate stiffness and ultimate load were noted between implants, all of the values exceeded published values for the human MPFL.

Clinical Relevance

This biomechanical study presents ASA cortical onlay fixation as a viable option for MPFL reconstruction. ASAs require less bone removal, potentially reducing the risk of patellar fracture and minimizing fixation complexity in the setting of open femoral growth plates. Future clinical studies will provide insight into successful tendon-to-bone healing, failure rates, and near- and long-term patient-reported outcomes.

Medial Patellofemoral Ligament Reconstruction Using the Medial Third of the Patellar Tendon: Camanho's Technique

The reconstruction of the medial patellofemoral ligament (MPFL) is an essential procedure in the surgical treatment of patellar instability. The medial third of the patellar tendon is a good graft option for this reconstruction, maintaining the insertion of the graft in the patella, with no need for hardware for patellar fixation. The objective of this article is to describe the MPFL reconstruction technique with the patellar tendon graft.

No Difference in Pullout Strength Between a Bio-inductive Implant and a Semitendinosus Tendon Graft in a Biomechanical Study of Medial Patellofemoral Ligament Repair Augmentation

Purpose

To compare the pullout strength of a bio-inductive implant (BI) used to augment a medial patellofemoral ligament (MPFL) repair with the pullout strength of semitendinosus graft in a biomechanical cadaveric model.

Methods

Six matched pairs of cadavers (12 knees) were used in the biomechanical testing comparing semitendinosus tendon (Semi-T) versus a BI. The Semi-T was harvested from 1 of the matched pairs. A standard double-bundle technique using 2 sockets in the upper two-thirds of the patella 15 mm apart was performed. After docking of the graft into the patella, the patella was dissected free of soft tissues and potted into a fixture to allow mechanical pull parallel to the transverse axis of the patella. The construct was pulled to failure.

Results

There was no statistically significant difference in pullout strength (P = .77) between the BI group (249.3 ± 36.3 N) and Semi-T group (235.0 ± 113.6 N) double-bundle constructs. In the Semi-T group, 50% of the specimens (3 of 6 knees) failed via anchor pullout and a fourth specimen failed at the suture-anchor interface (16.7%), whereas in the BI group, 16.7% of the specimens (1 of 6 knees) failed by anchor pullout. Although the Semi-T group (49.5 ± 14.1 N/mm) showed significantly greater stiffness than the BI group (13.8 ± 0.6 N/mm, P < .01), pullout strength in the Semi-T group was highly variable: 50% of the specimens (3 of 6 knees) with semitendinosus constructs failed at 5 mm of displacement or less via graft or anchor pullout. Maximum load, displacement at failure, stiffness, and load at 5 mm were compared between the augmented and non-augmented control specimens using a 2-tailed non-equal variance Student t test. For all comparisons, P < .05 was considered to indicate a statistically significant difference.

Conclusions

In this biomechanical study, augmentation of an MPFL reconstruction using a common double-bundle technique with a BI had the same pullout strength as a semitendinosus graft using the same technique in cadaveric knees.

Clinical Relevance

MPFL repair after a patellar dislocation may be inadequate to restore the strength of the native MPFL and prevent recurrent patellar instability. Recurrent instability of the patella can result in progressive injury to the soft tissue and articular cartilage of the patella and femur. It is important to study the techniques used for MPFL repair to continually improve patient outcomes. Further testing of these additional techniques and clinical studies are needed to evaluate the implants used to augment MPFL repairs.