Joshua S. Dines

Enhancement of Achilles tendon repair mediated by matrix metalloproteinase inhibition via systemic administration of doxycycline.

Collagenases or matrix metalloproteinases (MMPs) have been shown to play an important role in the matrix degradation cascade associated with Achilles tendon rupture and disease. The goal of this study was to examine the effects of daily administration of doxycycline (Doxy) through oral gavage on MMP activity and on the repair quality of Achilles tendons in vivo. Our findings indicate that Achilles tendon transection resulted in increasing MMP‐8 activity from 2 to 6 weeks post‐injury, with peak increases in activity occurring at 4 weeks post‐injury. Doxy adiministration at clinically relevant serum concentrations was found to significantly inhibit MMP activity after continuous treatment for 4 weeks, but not for continuous administration for shorter durations (96 h or 2 weeks). Extended doxy administration was also associated with improved collagen fibril organization, and enhanced biomechanical properties (stiffness, ultimate tensile strength, maximum load to failure, and elastic toughness). Our findings indicate that a temporal delay exists between Achilles tendon transection and associated increases in MMP‐8 activity in situ. Our findings suggest that inhibition of MMP‐8 at its peak activity levels ameliorates fibrosis development and improves biomechanical properties of the Achilles tendon.

Simvastatin Exposure and Rotator Cuff Repair in a Rat Model.

Simvastatin is a common medication prescribed for hypercholesterolemia that accelerates local bone formation. It is unclear whether simvastatin can accelerate healing at the tendon-bone interface after rotator cuff repair. This study was conducted to investigate whether local and systemic administration of simvastatin increased tendon-bone healing of the rotator cuff as detected by maximum load to failure in a controlled animal-based model. Supraspinatus tendon repair was performed on 120 Sprague-Dawley rats. Sixty rats had a polylactic acid membrane overlying the repair site. Of these, 30 contained simvastatin and 30 did not contain medication. Sixty rats underwent repair without a polylactic acid membrane. Of these, 30 received oral simvastatin (25 mg/kg/d) and 30 received a regular diet. At 4 weeks, 5 rats from each group were killed for histologic analysis. At 8 weeks, 5 rats from each group were killed for histologic analysis and the remaining 20 rats were killed for biomechanical analysis. One rat that received oral simvastatin died of muscle necrosis. Average maximum load to failure was 35.2±6.2 N for those receiving oral simvastatin, 36.8±9.0 N for oral control subjects, 39.5±12.8 N for those receiving local simvastatin, and 39.1±9.3 N for control subjects with a polylactic acid membrane. No statistically significant differences were found between any of the 4 groups (P>.05). Qualitative histologic findings showed that all groups showed increased collagen formation and organization at 8 weeks compared with 4 weeks, with no differences between the 4 groups at each time point. The use of systemic and local simvastatin offered no benefit over control groups. [Orthopedics. 2017; 40(2):e288-e292.].

Ulnar Nerve Issues in Throwing Athletes

Ulnar nerve injuries are not uncommon among throwing athletes. The anatomy of the ulnar nerve and the course in which it travels through the upper extremity make it susceptible to injury, especially when the elbow is loaded in the extremes that come with throwing sports such as baseball pitching. In addition to occurring in isolation, ulnar nerve symptoms may present in patients with ulnar collateral ligament (UCL) insufficiency. Postoperative ulnar nerve dysfunction is the most commonly cited complication after reconstructive surgery. This can be attributed to the fact that the ulnar nerve is in close proximity to the native ulnar collateral ligament and is at risk for injury during surgery. To identify and protect the nerve, Jobe in his original description of the procedure, dissected out the nerve from the cubital tunnel and then transposed the nerve anteriorly in a submuscular fashion after the reconstruction was performed. However, the dissection and transposition itself may also present a risk for postoperative ulnar neuropathy. In light of this, Jobe’s original surgical technique which has undergone several modifications in the surgical approach to the UCL and handling of the ulnar nerve, which has improved the postsurgical complication rate.

Combined Flexor-Pronator Mass and Ulnar Collateral Ligament Injuries

The anterior bundle of the ulnar collateral ligament (UCL) is the primary stabilizer against valgus stress in the elbow. However, when the UCL is compromised, the flexor-pronator mass becomes the primary dynamic valgus stabilizer of the elbow. Combined UCL and flexor-pronator mass injuries are a subset of medial elbow injuries sustained by overhead throwing athletes. Compared to athletes who suffer isolated UCL injuries, the group with combined UCL and flexor-pronator mass injuries tend to be older and have worse outcomes after surgical reconstruction. There are few studies describing these injuries in the orthopedic literature, and it is unclear what causes them to fail surgical management at a higher rate than UCL injuries alone. Treatment of this group requires a thorough history and physical exam, as well as a magnetic resonance imaging (MRI) for surgical planning. Based on the amount of flexor-pronator mass injury, different operative approaches may be warranted. It is important to counsel these patients about their prognosis, especially elite baseball players regarding their chances of returning to their previous level of play.

Ulnar Collateral Ligament Reconstruction: Docking Technique

Prior to Jobe’s description of a reconstruction technique for ulnar collateral ligament (UCL) insufficiency, the injury was career ending. Despite successful results in about 70 % of cases, concerns with elevation of the flexor-pronator mass, ulnar nerve complications and relatively large bone tunnels in the medial epicondyle of the humerus led to modifications to Jobe’s technique. One of the most novel modifications was the “docking technique.” Differences included: (1) arthroscopic evaluation and management, when indicated, of concomitant intra-articular pathology, (2) maintenance of the ulnar nerve in situ unless symptoms specifically indicate transposition, (3) use of a muscle splitting approach through the flexor mass, and (4) “docking” of the graft into a humeral socket. Ulnar preparation remained the same as originally described Jobe. These modifications facilitated improved graft tensioning while minimizing the number of large tunnels drilled in the relatively small medial epicondyle. Intraoperative morbidity was minimized by the muscle-splitting approach and the reservation of ulnar nerve transposition only when indicated based on preoperative exam. Clinical results have been excellent using this technique, and it is our preferred technique for UCL reconstruction.

History and Physical Exam on the Thrower’s Elbow

Overhead athletes frequently sustain injuries to their dominant elbow secondary to the high valgus and extension forces inherent to the throwing motion. The relatively unnatural motion of throwing can produce a myriad of pathological stresses on the structures about the elbow, namely tensile stresses medially, compression stresses laterally, and shear stresses posteromedially. Accurate diagnosis and treatment of elbow pain in the throwing athlete depends upon a detailed history, methodical physical examination, and appropriate ancillary tests when needed, as any of the above mentioned stresses may produce varying types of lesions in the elbow joint. The clinician must possess a thorough understanding of the functional anatomy and biomechanical characteristics of the complex elbow articulation to efficiently evaluate and diagnosis such pathologies in the thrower’s elbow.

Biologics and Patches

Over the past decade, surgical instrumentation and repair constructs have improved the biomechanical strength of rotator cuff repairs, making mechanical failure rare. Most recurrent rotator cuff tears are thought to be due to the compromised biological environment at the relatively avascular healing site. Treatments that augment the biology of rotator cuff healing provide the potential to improve patient outcomes following repair. Most of the research focusing on enhancing tendon healing is in the preclinical stages. The most promising of this research will be reviewed here, but the focus of the chapter will be on modalities available to surgeons now including platelet rich plasma (PRP) and patches. To date, results of PRP augmentation in the setting of large rotator cuff repairs are not very promising. Patches can help when used in the appropriate setting. It is important to note that patient selection is a critical element of improving outcomes. Perhaps the most effective way to currently improve the biological environment of rotator cuff repairs is to optimize medical conditions such as diabetes and smoking cessation.

Injections Including Platelet-Rich Plasma

In the overhead athlete, medial ulnar collateral ligament (MUCL) insufficiency can develop from the repetitive valgus loads across the elbow during the throwing motion. This injury can be potentially career ending for the athlete. Treatment options include conservative care or potential surgical intervention with ligament reconstruction. Given the prolonged recovery period after surgical intervention, other avenues for successful treatment of MUCL insufficiency have been explored including potential injections into the ligament including platelet-rich plasma (PRP). Recently, PRP has drawn interest as a tool for biologic augmentation of tendon and ligamentous healing as it is an autologous concentration of platelets and growth factors including vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1), fibroblast growth factor-2 (FGF-2), platelet-derived growth factor (PDGF), and transforming growth factor-s (TGF-s). Recent clinical work has shown that PRP injections into the MUCL may play a role in the management for the young overhead athlete that has acute damage to an isolated part of the ligament, and in those athletes that are unwilling or unable to undergo the extended rehabilitation required after surgical reconstruction of the ligament.