Erratum: Carpal Tunnel Release: Do We Understand the Biomechanical Consequences?

[This corrects the article DOI: 10.1055/s-0034-1394363.].

Flexor Tendon Repair With Looped Suture: 1 Versus 2 Knots.

PURPOSE: To assess the strength of flexor tendon repair with looped suture. We hypothesized that, after passing the intact looped suture in the desired repair configuration, splitting the loop and tying 2 independent knots would increase the strength of flexor tendon repair. METHODS: Thirty-two flexor tendons were harvested and were sharply transected in zone II. The tendons were repaired with a 4-strand core suture repair using 3-0 looped nonabsorbable nylon suture. The harvested tendons were randomly assigned and repaired with either a 1- or a 2-knot construct. The repaired flexor tendons were fixed in a servohydraulic material testing system and were loaded to failure either with uniaxial tension or cyclically. RESULTS: The average force at failure was 43 N for the 1-knot repair and 28 N for the 2-knot repair. The mode of failure of 15 of the flexor tendon repairs that were cyclically loaded to failure was suture pull-out. The average number of cycles and force in cyclic testing that caused failure of flexor tendon repairs was 134 cycles and 31 N for tendons repaired with looped 3-0 suture tied with 1 knot and 94 cycles and 33 N for tendons repaired with looped 3-0 suture tied with 2 knots. CONCLUSIONS: Our hypothesis was disproved by the results of this study. CLINICAL RELEVANCE: This study suggests that, when using looped suture, tying 2 independent knots instead of tying a single knot does not increase the strength of the flexor tendon repair.

Carpal tunnel release: do we understand the biomechanical consequences?

Carpal tunnel release is a very common procedure performed in the United States. While the procedure is often curative, some patients experience postoperative scar sensitivity, pillar pain, grip weakness, or recurrent median nerve symptoms. Release of the carpal tunnel has an effect on carpal anatomy and biomechanics, including increases in carpal arch width and carpal tunnel volume and changes in muscle and tendon mechanics. Our understanding of how these biomechanical changes contribute to postoperative symptoms is still evolving. We review the relevant morphometric and biomechanical changes that occur following release of the transverse carpal ligament.

Distinct effects of platelet-rich plasma and BMP13 on rotator cuff tendon injury healing in a rat model.

BACKGROUND: Although platelet-rich plasma (PRP) is used clinically to augment tendon healing, bone morphogenetic protein-13 (BMP13) may provide a better therapeutic avenue to improve early tendon healing and repair. HYPOTHESIS: Exogenous expression of BMP13 in tenocytes will up-regulate genes involved in tendon healing. Direct delivery of adenovirus-mediated BMP13 (AdBMP13) into the injured rat supraspinatus tendon will increase biomechanical properties. STUDY DESIGN: Controlled laboratory study. METHODS: Exogenous expression of BMP13 and the major growth factors in PRP (transforming growth factor-ß1 [TGF-ß1], vascular endothelial growth factor-A [VEGF-A], and platelet-derived growth factor-BB [PDGF-BB]) was accomplished by using recombinant adenoviral vectors. The expression of tendon- and matrix-associated genes in growth factor-treated tenocytes was analyzed by use of semiquantitative reverse-transcription polymerase chain reaction. A total of 32 rats with supraspinatus defect were divided into 4 groups and injected with adenovirus-containing green fluorescent protein (AdGFP; negative control), PRP, AdBMP13, or PRP+AdBMP13. All rats were sacrificed at 2 weeks after surgery, and tendons were harvested for biomechanical testing and histologic analysis. RESULTS: BMP13 up-regulated type III collagen expression compared with AdGFP control and PRP growth factors (P < .01). BMP13 and PRP growth factors each up-regulated fibronectin expression (P < .01). There was an increase in stress to failure in each of the 3 treatment groups (P < .05 for PRP; P < .01 for AdBMP13 or PRP+AdBMP13) compared with AdGFP control. AdBMP13 demonstrated higher stress to failure than did the PRPs (P < .01). The addition of PRP did not increase the BMP13-enhanced stress to failure or stiffness. The biomechanical results were further supported by histologic analysis of the retrieved samples. CONCLUSION: Exogenous expression of BMP13 enhances tendon healing more effectively than PRP as assessed by tendon- and matrix-associated gene expression, biomechanical testing, and histologic analysis. CLINICAL RELEVANCE: While PRP is used in the clinical setting, BMP13 may be explored as a superior biofactor to improve rotator cuff tendon healing and reduce the incidence of retears.

Tendinopathy treatment: where is the evidence?

Tendinopathy is a common and debilitating condition that results in significant deficits in performance and prolonged time away from activity. For this reason, much effort has been placed in defining beneficial and cost-effective treatments. This review has outlined the current literature on some of the most widely used therapies for cases of tendinopathy. As such, recommendations remain limited by the evidence available. The variability in both quantity and quality of research into tendinopathy treatments makes it difficult to make definitive treatment recommendations. In general, however, a reasonable first line of treatment for tendinopathy should include a course of NSAIDs and eccentric exercise-based physical therapy. Corticosteroid injections seem to offer excellent short-term pain relief but lack long term efficacy. Alternative injections, such as PRP, have shown short-term efficacy for tendinopathy sufferers; data are lacking to support sclerosing agents and proteinase inhibitors. Operative management seems to offer some benefit in symptomatic relief but carries a higher complication rate than other treatment options and should be reserved only for patients recalcitrant to other more conservative options. Although the inability to make definitive therapeutic recommendations in some instances is discouraging, it is important to note that a lack of high-quality evidence supporting specific treatments does not necessarily imply that they are inherently ineffective. Given the growing prevalence of tendinopathy and the impact it has on the general public, it is more important now than ever to continue the search for the most effective and accessible treatment modalities.

Lim 1 is required for nephric duct extension and ureteric bud morphogenesis.

The nephric duct plays a central role in orchestrating the development of the mammalian urogenital system. Lim 1 is a homeobox gene required for head and urogenital development in the mouse but most Lim 1-deficient embryos die by embryonic day 10. To determine the role of Lim 1 in the development of the nephric duct, we conditionally removed Lim 1 in the nephric epithelium just after the nephric duct begins to form using a floxed allele of Lim 1 and Pax2-cre transgenic mice. We report that Lim 1 conditional knockout mice have renal hypoplasia and hydronephrosis. Developmental studies revealed that the caudal portion of the nephric duct did not reach the urogenital sinus at embryonic day 10.5, formation of the ureteric bud was delayed, the ureteric bud was smaller and branching of the ureteric bud reduced. We also found that the nephric duct was generally not maintained and extension of the Müllerian duct inhibited. Molecular analysis indicated that Pax2 was expressed normally but the expression of Wnt9b and E-cadherin in the nephric duct was markedly altered. These results suggest that Lim 1 influences nephric duct extension and ureteric bud outgrowth by regulating and or maintaining the differentiation of the nephric epithelium.