Cyclic Testing of 3 Medial Patellofemoral Ligament Reconstruction Techniques

Abstract

Background:Several techniques are available to secure the graft to the patella during medial patellofemoral ligament (MPFL) reconstruction. The biomechanical properties of these techniques remain unknown.Purpose:To compare the biomechanical properties of 3 MPFL patellar fixation techniques: bone tunnels (BT), PushLock anchors (PL), and tenodesis screws (TS).Study Design:Controlled laboratory study.Methods:Forty-five MPFL reconstructions were performed using 3 different reconstruction techniques (BT, PL, and TS). The specimens were randomly assigned, with 15 specimens in each of the 3 groups. Cyclic loading (500 cycles) and load-to-failure testing were performed. Gap formation after 100 and 500 cycles, ultimate load to failure, and stiffness were measured.Results:Six constructs failed during cyclic loading, 5 in the PL group (33%) and 1 in the TS group (6.7%). After 100 cycles, differences in gap formation were found between the PL and BT groups (4.48 vs 3.62 mm, P < .03) and between the PL and TS groups (4.48 vs 2.28 mm, P < .0001). After 500 cycles, differences in gap formation were found between the BT and TS groups (6.63 vs 4.16 mm, P < .002) and between the PL and TS groups (7.89 vs 4.16 mm, P < .005). The PL group was found to have a lower ultimate load to failure when compared with the BT group (161.4 vs 258.3 N, P = .019) and the TS group (161.4 vs 237.1 N, P = .009). Group differences in stiffness did not reach statistical significance among the 3 groups (PL, 33.72 N/mm; BT, 37.50 N/mm; TS, 43.00 N/mm).Conclusion:The TS and BT groups have more ideal biomechanical properties than the PL group, as demonstrated by less displacement during cyclic loading and a higher load to failure.Clinical Relevance:Fixation of the patellar limbs during MPFL reconstruction may be optimized with the use of TS or BT over a PL technique.

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

“…These studies are summarized in Table 1 . 4 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18

Fig 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart detailing the database search and inclusion/exclusion process. (MPFL, medial patellofemoral ligament.)

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“…Of the 6 studies that evaluated patellar fixation, all 6 reported on ultimate load to failure and 5 commented on stiffness. 4 , 11 , 12 , 13 , 14 , 15 Of the 3 studies that evaluated femoral fixation, all 3 studies commented on ultimate load to failure and 2 commented on stiffness. 16 , 17 , 18 …”

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

“… 10 In another study, it was reported that patellar fixation performed with anchor fails easier than the patellar bone tunnel. 11 Zanon et al. reported a surgical technique in double-bundle MPFL reconstruction using a single patellar tunnel directed toward the cranial direction.…”

“…10 In another study, it was reported that patellar fixation performed with anchor fails easier than the patellar bone tunnel. 11 Zanon et al reported a surgical technique in doublebundle MPFL reconstruction using a single patellar tunnel directed toward the cranial direction. 3 In the technique reported by the authors, the lateral end of the patellar tunnel is opened to the superior pole, where the weaker bone is located.…”

Interference Screw Versus Suture Anchors for Femoral Fixation in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Study

“…8,24,28 Multiple prior studies have reported the biomechanical properties of these fixation methods on the patellar side. 13,19,22,26,27 Adequate graft fixation to the femur is also critical to preventing the laxity of the reconstructed MPFL. Femoral fixation is commonly performed using an IS placed at the MPFL insertion point defined by Schöttle et al 29 However, the IS method of femoral fixation has some possible disadvantages, including the potential for injury to the distal femoral physis, which can lead to iatrogenic growth alteration and ultimately result in angular growth deformities.…”