Faculty Bibliography

BACKGROUND: Arthroscopically assisted anterior cruciate ligament reconstruction using a bioabsorbable tibial fixation screw is occasionally complicated by pretibial cyst formation. The few case reports describing pretibial cyst formation noted several graft types and fixation techniques, making it difficult to establish one etiology. Some literature suggests cysts form from communication between the joint and pretibial area leading to extravasation of joint fluid, maturing into a cyst. We propose the development of cysts after PLLA screw use may be related to a foreign body reaction. QUESTIONS/PURPOSES: We propose this foreign body reaction (1) relates to the biochemical breakdown of bioabsorbable materials; and (2) differs from cystic formations resulting from joint communication. METHODS: We retrospectively reviewed seven patients who developed pretibial cysts at least 2 years after original primary ACL reconstruction surgery. MRI was used to visualize the extent of cystic formation. Cysts were treated by debridement with specimens sent for histologic analysis. Cyst appearance had a 3-year incidence of 5%. RESULTS: No cyst had an infectious etiology. In all cases, the tibial screw outline was present on MRI, although intraoperatively, the screw was substantially decomposed. Grafts were well incorporated and none of the knees demonstrated anterior laxity. Histologically, cyst material contained fragments of PLLA surrounded by foamy histiocytes, suggesting a foreign body reaction. No cysts recurred. CONCLUSIONS: Tibial cysts occur in a subset of patients undergoing ACL reconstruction using a bioabsorbable PLLA interference screw. We suspect they arise from a foreign body response to the screw breakdown. Removal is well tolerated. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND: Techniques for reconstruction of the dislocated acromioclavicular (AC) joint abound. Most, however, do not address the injured AC ligaments and capsule. Evidence exists supporting the horizontal stabilizing effect of these ligaments on the AC joint. A novel AC and coracoclavicular (CC) reconstruction technique with an intramedullary free-tissue graft secured by suture buttons is low-profile, technically straightforward, and reproducible. HYPOTHESIS: A novel intramedullary AC reconstruction will strengthen an isolated free-tissue reconstruction of the CC ligaments. STUDY DESIGN: Controlled laboratory study. METHODS: Six cadaveric matched pair shoulders were tested with a custom testing system. Anterior-posterior and superior-inferior AC joint displacements (mm) were measured with AC joint compressions of 10 N, 20 N, and 30 N, and with translational loads of 10 N and 15 N. The same measurements were made after performing either a free-tissue tendon allograft CC reconstruction, or a free-tissue graft reconstruction of the CC and AC ligamentous complexes in the corresponding contralateral matched shoulder. The AC ligamentous complex was reconstructed with an intramedullary free-tissue graft secured by suture buttons. Load-to-failure testing was then performed on each construct. A paired t test was used for statistical analysis (P < .05). RESULTS: Mean anterior-posterior translation of the reconstruction of the CC and AC ligamentous complexes was 50% or less than that of the CC reconstruction in all loading conditions (P < .05). Mean superior-inferior translation did not differ among the groups. Overall load-to-failure testing did not differ between groups. CONCLUSION: Intramedullary AC complex reconstruction utilizing free-tissue graft for reconstruction of both the CC and AC ligaments demonstrates significantly greater initial horizontal stability than a free tissue isolated CC reconstruction and is similar to intact specimens. CLINICAL RELEVANCE: This novel intramedullary AC ligament reconstruction may be considered when seeking to improve horizontal stability in an anatomical CC ligament reconstruction.

This biomechanical study compared 2 repair techniques for high-grade, partial, articular-sided supraspinatus tendon tears of the rotator cuff: transtendon in situ repair and tear completion with repair. Standardized, 50% partial, articular-sided supraspinatus lesions were created in 10 pairs of matched fresh, frozen cadaveric shoulders: 10 underwent partial lesion repair with an in situ transtendon technique using 2 suture anchors. In the contralateral 10 shoulders, the partial lesion was converted to a full-thickness tear and repaired with a double-row technique, using 4 suture anchors. Cyclic loading to failure of the supraspinatus tendon was performed using a material testing machine. Gap formation was measured for each rotational position and each incremental load. The in situ transtendon repair had statistically significant less gapping (P = .0001) and higher mean ultimate failure strength (P = .0011) than the double-row repair. In situ transtendon repair was biomechanically superior to tear completion for partial, articular-sided supraspinatus tears.