The effect of autologous Achilles bursal tissue implants in tendon-to-bone healing of rotator cuff tears in rats.

BACKGROUND: The aim of this study was to investigate the influence of autologous bursal tissue derived from the Achilles bursa on tendon-to-bone healing after rotator cuff tear repair in a rat model. METHODS: A total of 136 Sprague-Dawley rats were randomly assigned to either an untreated or a bursal tissue application group or biomechanical testing and histologic testing after rotator cuff repair. After separating the supraspinatus tendon close to the greater tuberosity, the tendon was reattached either unaltered or with a bursal tissue interposition sewn onto the interface. Immunohistologic analysis was performed 1 and 7 weeks after supraspinatus tendon reinsertion. Biomechanical testing of the tendon occurred 6 and 7 weeks after reinsertion. RESULTS: Immunohistologic results demonstrated a significantly higher percentage of Type II collagen (P = .04) after 1 and 7 weeks in the tendon-to-bone interface using autologous bursal tissue in comparison to control specimens. The bursa group showed a significantly higher collagen I to III quotient (P = .03) at 1 week after surgery in comparison to the 7-week postsurgery bursa groups and controls. Biomechanical assessment showed that overall tendon stiffness (P = .002) and the tendon viscoelasticity in the bursa group (P = .003) was significantly improved after 6 and 7 weeks. There was no significant difference (P = .55) in force to failure between the bursa group and the control group after 6 and 7 weeks. CONCLUSION: Autologous bursal tissue derived from the Achilles bursa and implanted to the tendon-to-bone interface after rotator cuff repair facilitates a faster healing response to re-establish the biologic and biomechanical integrity of the rotator cuff in rats.

Migration of Mesenchymal Stem Cells of Bursal Tissue after Rotator Cuff Repair in Rats.

Purpose The purpose of this study is to verify migration of mesenchymal stem cells of bursal tissue into the healing site after rotator cuff repair in rats. Methods Fischer rats and green fluorescent protein (GFP)-transgenic rats were used. Bursal tissue from GFP rats was isolated and transplanted into tendon repair sites in Fischer rats. We examined the histology of the rotator cuff and the proportion of GFP-positive cells in the repaired rotator cuff 1, 3, and 6 weeks after surgery. Results Cell migration was observed during the third and sixth week after surgery. We also found mesenchymal stem cells and formed bursal cluster patterns in the repaired rotator cuff tendons. Conclusion Mesenchymal stem cells migrated from bursal tissue and infiltrated the repaired rotator cuff tendons. Clinical Relevance Mesenchymal stem cells from bursal tissue can contribute to the healing progress of the repaired rotator cuff.

Graft maturation of autologous chondrocyte implantation: magnetic resonance investigation with T2 mapping.

BACKGROUND: Autologous chondrocyte implantation (ACI) using tissue-engineered cartilage is a successful therapy for full-thickness cartilage lesions in the knee joint. However, in vivo graft maturation is still unclear. PURPOSE: The aim of this prospective study was to analyze graft maturation after ACI in the knee using objective T2 mapping in correlation with the clinical outcomes within a 3-year postoperative course. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 13 patients with isolated cartilage defects of the knee were treated with Novocart 3D, a matrix-based ACI procedure in the knee joint. The patients had complete data from International Knee Documentation Committee (IKDC) scores and MRI examinations for 6 to 36 months postoperatively. All cartilage defects were arthroscopically classified as Outerbridge grades III and IV. The mean area of the cartilage defect was 5.6 cm(2). Postoperative clinical and MRI examinations were conducted at 6, 12, 24, and 36 months after surgery. The modified magnetic resonance observation of cartilage repair tissue (MOCART) score was used to evaluate the quality and integration of the Novocart 3D implants on MRI. The T2 relaxation time values of the ACI graft and healthy native cartilage areas were determined to assess graft maturation using T2 mapping. RESULTS: The T2 relaxation times of the ACI graft showed significant improvement, with decreasing values from 41.6 milliseconds at 6-month follow-up to 32.4 and 30.9 milliseconds after 24 and 36 months, respectively. These values were similar to the T2 relaxation times of the native surrounding cartilage. There was no correlation between the clinical outcomes (IKDC score) and T2 relaxation time values. CONCLUSION: The T2 relaxation time in the repaired tissue showed similar values compared with normal hyaline cartilage. Graft maturation after ACI in the knee joint needs at least 1 year, with ongoing adjustment of the T2 relaxation time values compared with native surrounding cartilage. A correlation between increasing ACI graft maturation and clinical outcomes (IKDC score) could not be found with the data available.

Early resumption of physical activities leads to inferior clinical outcomes after matrix-based autologous chondrocyte implantation in the knee.

PURPOSE: Matrix-based autologous chondrocyte implantation is a well-established operation procedure for full cartilage defects. When to resume physical activity after matrix-based autologous chondrocyte implantation is controversial. Our hypothesis was that early resumption of physical activity leads to a worse clinical outcome after matrix-based autologous chondrocyte implantation in the knee two years post-operatively. Physical activity is defined as any kind of impact sport. METHODS: Forty-four patients with cartilage defects of the knee were treated with matrix-based autologous chondrocyte implantation (Novocart3D). All patients were assessed preoperatively and after a period of 24 months with the University of California Los Angeles (UCLA) Activity score. The return to physical activities or sports after matrix-based autologous chondrocyte implantation was documented. Patients were evaluated using the International Knee Documentation Committee Knee Examination Form and visual analogue scale for pain after 6, 12 and 24 months. RESULTS: Fifty-five percent showed an unchanged level of physical activity in the UCLA Activity score post-operatively. About 35% showed a lower level and 10% a higher level of physical activity. The average return to physical activities or sports after matrix-based autologous chondrocyte implantation procedure was 10.2 months. Patients with a later return of sports after 12 months showed significantly better clinical results after two years. In particular, patients who started practicing impact sport after 12 months post-operatively showed significantly better results. CONCLUSION: Resuming physical activity including impact sports without waiting at least 12 months after the operation leads to inferior outcomes up to 24 months after matrix-based autologous chondrocyte implantation. LEVEL OF EVIDENCE: Level IV.

Sports activities after medial unicompartmental knee arthroplasty Oxford III-what can we expect?

PURPOSE: Excellent long-term results have been reported for implantation of unicompartmental knee arthroplasty (UKA). In many patients the desire for improvement in function often includes an aspiration to return to sports. The purpose of our study was to evaluate physical activities after medial Oxford-III (Biomet) UKA surgery. METHODS: Patients' physical activity before and after the surgery was assessed using a self reporting questionnaire. We used the Oxford knee scoring system (OKS), the WOMAC-, the Knee society- (KSS) and the UCLA-score to assess postoperative knee function. The mean follow-up was 4.2 years. The female-to-male ratio was 1.3:1. The mean age at surgery was 65.3 years. RESULTS: Of the 131 patients studied 78 participated in some kind of sports before surgery (mean age 64.4 years), while 53 patients did not perform any sports (mean age 66.5 years) (p > 0.05). At follow-up the patients in the active group were significantly younger than the patients in the inactive group (p < 0.05). The majority of patients (80.1 %) returned to their level of sports activity after UKA surgery. Six patients took up sports after surgery while 15 patients stopped their sports. Among the active patients we found a shift from high- towards low-impact sports. The active patients had significantly higher scores for the OKS, KSS, WOMAC and UCLA score. The complication rate was comparable in both groups. CONCLUSION: Our study demonstrates that a high degree of patient satisfaction in terms of sports activity can be achieved using the Oxford-III UKA for medial osteoarthritis.