Arthroscopic Repair of Retracted Large and Massive Rotator Cuff Tears with and without Augmentation with a Bio-Inductive Collagen Implant Reveals Substantial and Comparable Clinical Improvement.

PURPOSE: The study objective was to compare clinical and imaging results after repair of retracted large and massive full-thickness rotator cuff tears, including revision repairs, with and without augmentation with a bio-inductive collagen implant. METHODS: The study group comprised 24 patients (17 males) with retracted 2 or 3 tendon rotator cuff tears undergoing arthroscopic repair followed by onlay augmentation with a bio-inductive collagen implant. The control group comprised 24 patients (19 males) matched by tear size undergoing repair without augmentation. Mean patient age at repair in both groups was 61 years. Active range of motion (ROM) and patient-reported outcomes (PROs) were recorded before and after surgery. Noncontrast high-field magnetic resonance imaging (MRI) was obtained in 20/24 collagen implant patients and 17/24 control patients at minimum 6 months follow-up to assess tendon healing. RESULTS: American Shoulder and Elbow Surgeons and Simple Shoulder Test scores improved from 35 to 86 and 3.6 to 9.3, respectively, in the collagen implant group and from 39 to 87 and 3.9 to 9.7 in the control group. The visual analog score-pain improved from 6.0 to 0.9 and from 5.9 to 0.9 in the collagen implant and control groups, respectively (P < .001 for all). Overall improvements in ROM and PROs were similar in both groups. MRI revealed intact repairs in 11/20 (55%) patients in the patch group and 9/17 (53%) in the control group. Two patients in each group were revised to reverse shoulder arthroplasty. CONCLUSIONS: Arthroscopic repair of retracted large and massive rotator cuff tears, including revision repairs, with and without augmentation using a bio-inductive collagen implant results in substantial and comparable early clinical improvement, although predictable healing remains elusive. Further work is needed to optimize patient selection for massive rotator cuff repair and define more precisely the indications for augmentation of these repairs using the collagen implant. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Suitability of bioresorbable cages for anterior cervical fusion.

OBJECT: The authors conducted a pilot study to determine whether a bioresorbable intervertebral fusion device composed of 85/15 polylactide-polyglycolide (PLA-PGA) copolymer packed with bone autograft is a suitable alternative to promote arthrodesis after anterior cervical discectomy (ACD) in a caprine model. METHODS: The caprine cervical spine model has been used to evaluate interbody healing and fusion after application of bone grafts and instrumentation. Whether a bioresorbable device is suitable for facilitating intervertebral bone union has not been determined. Twelve goats underwent two-level ACD and fusion; eight received bioresorbable cages packed with autologous bone, and four received autologous bone alone. Goats were maintained without an orthosis and after 12 weeks underwent physical, radiographic, and histological evaluation. Cages had structurally degraded, and two had become extruded. Stable intervertebral union developed in three (19%) of 16 cage-implanted interspaces, and one (14%) of seven bone autograft-implanted interspaces; each was judged manually to be rigid (Grade 2), radiographically to be bridged by new osseous densities (Grade 2), and histologically to have marked new bone formation (Grade 3). A primarily fibrous union, however, stabilized the cage-implanted interspaces, and eight (50%) had developed a 4 to 6-mm foreign body granuloma. These interposed soft tissues were not present in the stable autologous bone-implanted interspace, which had successfully become fused. CONCLUSIONS: Interbody cages composed of 85/15 PLA-PGA copolymer contributed to a stable fibrous union, degraded. and produced granuloma after 12 weeks. Additional evaluations are necessary to determine whether other copolymer mixtures, or other bioresorbable materials, can contribute to an arthodesis without deleterious consequences.

Cervical spine fusion with bioabsorbable cages.

OBJECT: Although it improves rates of fusion in surgical arthrodesis, conventional spinal instrumentation is associated with several risks, including hardware extrusion that injures adjacent anatomical structures, and disuse osteopenia as a result of stress shielding. The long-term effects of indwelling spinal instrumentation, although incompletely documented, may be detrimental. One way to avoid such problems would be to use bioabsorbable implantation devices. In this pilot study, performed in 1998 and 1999, the authors evaluated the use of a bioabsorbable interbody fusion device in a goat cervical spine model. METHODS: Forty-two goats underwent two-level anterior cervical discectomy and fusion: eight received iliac crest autograft; 16 received a cage implant composed of 70:30 poly(L-lactide-co-D,L-lactide)/polyglycolic acid (70:30 PLDLLA/PGA) filled with either autograft or recombinant human bone morphogenetic protein-2 (rhBMP-2); and 18 received a cage implant composed of 85:15 PLDLLA/PGA filled with either autograft or rhBMP-2. Animals were killed at 3, 6, and 12 months postsurgery, and their cervical spines were evaluated histologically, radiographically, and physically for fusion. A primarily fibrous union was demonstrated in all animals killed at 3 months. At 6 months, bone trabeculae had become more prominent and the fibrous response less so in all cohorts. This occurred most frequently in the animals that underwent fusion with the 70:30 PLDLLA/PGA cages filled with rhBMP-2, in which 63% attained a histologically confirmed union that contained quantitatively more bone and less fibrous tissue than in the other cohorts; 63% of the unions in the aforementioned cohort were graded quantitatively as being stable. CONCLUSIONS: In this study the authors have established that the 85:15 PLDLLA/PGA cages are absorbed too quickly to be functionally useful in this model. The 70:30 PLDLLA/PGA cages worked as well as tricortical autograft when filled with cancellous autograft, and better when filled with rhBMP-2. At 6- and 12-month follow-up review, the 70:30 PLDLLA/PGA cages had not yet begun to be absorbed. There was little if any inflammatory response to these cages at 6 months. Future studies should include biomechanical and microradiographic testing, and a longer follow-up period is necessary in this model to determine when the 70:30 PLDLLA/PGA cages are absorbed.