The Biomechanical Effects of Limited Lateral Retinacular and Capsular Release on Lateral Patellar Translation at Various Flexion Angles in Cadaveric Specimens

Abstract

Purpose: To determine the biomechanical effect of limited lateral retinacular and capsular release on lateral patellar translation as a function of constant force at various knee flexion angles. Methods: Six pairs of bilateral cadaveric knee specimens (12 knees) were obtained from a tissue bank, dissected, and potted in a perfect lateral position based on fluoroscopy. A direct lateral force was applied to the patella through an eye screw in the midpoint of the lateral patella, and each knee underwent testing in the intact state and after lateral retinacular and capsular release. All knees were tested at 0 , 10 , 20 , 30 , 45 , 60 , and 90 of flexion using a custom-machined jig on a materials testing system with a 20-N lateral force applied to the patella. Patellar displacement was recorded and compared for each specimen. Results: Lateral displacement was significantly greater at all degrees of flexion for the lateral-release specimens than for an intact lateral retinaculum (P < .05). Compared with intact specimens, lateral-release specimens experienced 30% more translation at 0 of flexion and between 6% and 9% more lateral translation at 10 to 90 of flexion. Conclusions: Lateral retinacular and capsular release results in significantly increased lateral patellar translation at all flexion angles compared with intact specimens. This finding suggests that the lateral retinaculum may function as a significant restraint to lateral translation even with intact medial soft-tissue restraints. Clinical Relevance: Arthroscopic and open limited lateral retinacular releases should be performed with extreme caution when treating lateral patellar instability given the lateral retinaculum's apparent role as a secondary restraint.

Lateral Patellar Retinaculum Z-Lengthening

“…Additionally, a competent lateral retinaculum has been confirmed in biomechanical studies to prevent lateral patellar instability. 11 Besides patellar instability, LRL would be indicated for patellofemoral pain secondary to lateral patellar hypercompression syndrome that is refractory to conservative treatment. 5 Although LRR can also be performed without a formal arthrotomy of the joint by keeping the synovial layer intact and cutting the capsular layer, LRL as an alternative offers several advantages (Table 2).…”

Surgical Technique for Obligate Flexion Patellar Dislocation: Medial Patellofemoral Ligament Reconstruction, Distal Femoral Osteotomy, Quadricepsplasty, and Lateral Retinacular Reconstruction with Dermal Allograft

“…7 In addition, biomechanical studies have demonstrated the importance of the lateral retinacular structures in preventing increases in medial and lateral patellar translation and alterations of patellar tracking. [8][9][10][11] Because of the importance of the lateral retinaculum, we do not recommend performing lateral release procedures and instead suggest performing lateral lengthenings to preserve the overall integrity of the lateral structures. [12][13][14] As described in this technique, it may be difficult to perform a lateral lengthening because of either poor tissue quality or the significant extent to which a lengthening would need to be performed.…”

Arthroscopy‐controlled medial reefing and lateral release for recurrent patellar dislocation: clinical, radiologic outcomes and complications

“…After all the arthroscopic procedures, percutaneous lateral retinacular release was performed in all patients to prevent arthritic change by reducing the patellofemoral joint pressure [ 12 ]. This release procedure was performed as previously described by Randal et al [ 13 ].…”