Biomechanical comparison of the Achillon tendon repair system and the Krackow locking loop technique.

BACKGROUND: The Achillon" Achilles tendon repair system combines the benefits of open repair and percutaneous repair and has excellent clinical results with minimal complications. The Krackow locking loop has been the standard suture technique for many surgeons in open Achilles repair. We determined to see how the Achillon repair compared with the Krackow locking loop in a biomechanical pull-out study. METHODS: Paired lower limbs of ten human cadavers were randomly split to receive repair via Krackow locking loop or via Achillon in concordance with the manufacturer's manual. Following repair, the study groups were subjected to the same tissue processing and tensioned to failure in an Instron" 8841 device. From load-displacement curves, initial linear stiffness, load to failure, and work to failure were determined. RESULTS: The predominant mechanism of failure for the Krackow stitch was the breakage of the sutures or knots. The predominant failure mechanism of the Achillon repairs was the tearing of the suture loops through the tendon tissue. Repairs using the Krackow stitch possessed an average maximum load to failure of 128.3+/-30.3 N and a work to failure of 2199.1+/-669.7 N mm. After excluding outliers, repairs with the Achillon technique resulted in a maximum failure load of 178+/-35.4 N and a work to failure of 3999.8+/-942.7 N mm that were both significantly higher than the Krackow stitch (p<0.05). The initial stiffness of the repairs was significantly higher using the Krackow stitch (10.4+/-2.0 N/mm) compared to the Achillon technique (6.6+/-2.3 N/mm) (p<0.05). CONCLUSION: The results indicate a properly performed Achillon repair can be stronger (higher load to failure) and tougher (higher work to failure) than an open repair using the Krackow locking loop, although the Krackow repair tends to be stiffer prior to plastic deformation in this model. CLINICAL RELEVANCE: Applied correctly, the Achillon repair system offers an effective, minimally invasive alternative to traditional open repair.

Potential dangers of tension band wiring of olecranon fractures: an anatomic study.

PURPOSE: Displaced olecranon fractures are often amenable to treatment with open reduction and tension-band wiring. The purpose of this study is to examine the relationships of the tips of K-wires used in a tension-band construct to volar neurovascular structures in the proximal forearm and the proximal radioulnar joint. METHODS: We performed simulated percutaneous pinnings of the proximal ulna under fluoroscopic guidance on 15 cadavers with intact proximal ulnas. The K-wires were drilled obliquely through the tip of the olecranon process and directed to engage the anterior ulnar cortex, distal to the coronoid. Using calipers, we measured the distance from the tip of each pin to the anterior interosseous nerve (AIN), ulnar artery, proximal radioulnar joint (PRUJ), and volar cortex of the ulna, as well as the distance from the volar cortex of the ulna to the AIN and ulnar artery. The angle created by the K-wires and the longitudinal axis of the ulna was measured on both anteroposterior and lateral radiographs. RESULTS: The distance from pin tip to the AIN and ulnar artery measured a mean of 16 mm with a standard deviation of 6 mm and 14 mm with a standard deviation of 5 mm, respectively, with 1 pin abutting the artery. The shortest distance from both the AIN (11 ± 5 mm) and the ulnar artery (8 ± 6 mm) was measured with the shallowest angle of insertion, ranging from 10° to 14.9° on lateral radiographs. The mean distance between the pin tip and the PRUJ measured 7 mm with a standard deviation of 4 mm, with 3 pins penetrating the PRUJ. CONCLUSIONS: The impaction of K-wires under the triceps is often approximately 1 cm, which is similar to the distance of the K-wire tips to the AIN and ulnar artery. Our findings suggest that larger insertion angles might help avoid neurovascular injury when the insertion point of the K-wires is at or just proximal to the tip of the olecranon. In this study, the safe zone for pin insertion on the anteroposterior view is 0° to 10°, and on the lateral view it is 20° to 30°. CLINICAL RELEVANCE: This anatomic study was done to diminish the chance of complications resulting from K-wire placement during tension-band wiring for olecranon fractures.

Stasis predisposes ileal pouch inflammation in a rat model of ileal pouch-anal anastomosis.

BACKGROUND: While restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) has become the definitive surgical treatment for patients suffering from chronic ulcerative colitis (CUC), pouchitis still remains a major late complication. Fecal stasis has been implicated in the etiology of ileal inflammation; however, the mechanism(s) remain unclear, in part due to the lack of an animal model. Our goal was to surgically mimic the IPAA procedure in a rat to investigate the hypothesis that stasis leads to biochemical changes that predispose the ileal pouch to inflammation. MATERIALS AND METHODS: Thirty-two Sprague-Dawley rats underwent total colectomy with either straight ileorectal (IRA) or IPAA, and 11 nonoperated rats served as controls (Controls). Twenty-one d postoperatively, 48 h serial barium radiographs and 12 h charcoal transit follow-through studies were performed. Following sacrifice, ileal tissue was harvested for the measurement of myeloperoxidase activity (MPO) activity, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) mRNA levels, and histology. RESULTS: Serial barium radiographs showed stasis in the ileal pouch compared with IRA animals, and charcoal transit times that were two times longer (P ≤ 0.05) than that in the straight IRA rats. Ileal pouch MPO levels were significantly elevated in the IPAA rats compared with the straight IRA rats. ICAM-1 and VCAM-1 mRNA levels were not associated with neutrophil infiltration. CONCLUSIONS: These studies showed that ileal pouch stasis predisposes biochemical and histological evidence of ileal pouch mucosal inflammation. Studies such as this may provide the rationale for novel, adjunct therapies for the management of pouchitis in patients having undergone IPAA for CUC.

Influence of temporary chondroitinase ABC-induced glycosaminoglycan suppression on maturation of tissue-engineered cartilage.

OBJECTIVE: A fundamental challenge of cartilage tissue engineering has been the inability to promote collagen synthesis up to native levels. In contrast, recent protocols have demonstrated that glycosaminoglycans (GAG) can be synthesized to native levels in 4-6 weeks of in vitro culture. We hypothesize that rapid GAG synthesis may be an impediment to collagen synthesis, possibly by altering transport pathways of nutrients or synthesis products. In this study, this hypothesis is tested by inducing enzymatic GAG loss in the early culture period of cartilage tissue constructs, and monitoring collagen content at various time points after cessation of enzymatic treatment. METHODS: In Study 1, to induce breakdown of proteoglycans, chondroitinase ABC (CABC, 0.002U/mL) was continuously added into the culture media for the initial 4 weeks of culture or for 2 weeks starting on day 14 of culture. In Study 2, multiple transient CABC treatments (0.15U/mL, for 2 days) were applied to the matured tissue-engineered constructs. RESULTS: Continuous and transient CABC treatments significantly increased the collagen concentration of the constructs, improving their tensile properties. The GAG content of the treated constructs recovered quickly to the pretreatment level after 2-3 weeks. CONCLUSIONS: This study demonstrates that tissue-engineered cartilage constructs with improved tensile properties can be achieved by temporarily suppressing the GAG content enzymatically.

Posterior shoulder instability: comprehensive analysis of open and arthroscopic approaches.

Whether open surgery and arthroscopic repair of posterior shoulder instability have similar success rates remains unknown, but the literature suggests that arthroscopic soft-tissue stabilization procedures equal open surgery in managing posterior shoulder instability. A comprehensive PubMed computer search of the English-language literature from 1988 to 2004 was performed using the key phrase posterior shoulder instability. Studies included in our analysis addressed the surgical treatment of recurrent posterior instability and multidirectional instability with primarily a posterior component of instability; studies were excluded if their minimum follow-up was less than 1 year, if their patients had a history of habitual posterior shoulder instability, or if their patients had either bony procedures or thermal capsulorrhaphy. Data collected from each study included patient demographics, instability classifications (traumatic vs atraumatic), previous shoulder stabilizations, and clinical outcomes. After identifying and reviewing 283 abstracts, we found that 16 articles fulfilled the inclusion criteria--9 open studies (173 patients) and 7 arthroscopic trials (186 patients). The 2 treatment groups had similar sex distributions (P> .25). Mean age was 23 years for the open group and 26 years for the arthroscopic group (P< .02). Clinical outcomes were rated satisfactory by 72% of patients in the open group and 83% of patients in the arthroscopic group (P< .55), controlling for age. Eighty-five percent of patients treated with an open technique and 81% of patients treated arthroscopically returned to sports (P< .82). This study demonstrated no statistical difference in clinical outcomes for patients treated with either open or arthroscopic surgery for posterior shoulder instability.