Is the radial groove a myth? Is the radial nerve in direct contact with the posterior humerus?

BACKGROUND: The radial groove is known as a sulcus on the posterior humerus and protects the radial nerve from adjacent muscle and soft tissue. In the literature, there exists heterogeneity regarding the presence of an actual radial groove and the radial nerve's interaction with the periosteum of the humerus. This study aimed to determine if there is a real radial groove, "sulcus," and define the relationship between the radial nerve and the periosteum of the posterior humerus. METHODS: Eighteen fresh-frozen cadaveric specimens were dissected using a posterior triceps splitting approach. The radial nerve's interaction with the periosteum of the humerus was determined. The presence of a visible and palpable radial groove was also examined. RESULTS: In 56% of specimens, the radial nerve was directly seated over the periosteum of the posterior humerus (direct contact between the nerve and bone). In comparison, 44% of specimens had a layer of the medial head of the triceps brachii muscle fibers interposition between the nerve and bone. 89% of specimens had no visible or palpable radial groove. In 11% of specimens, there was mild palpable depression. CONCLUSION: This study shows that the radial groove may not exist and is probably not a true anatomical structure. In addition, the nerve is in direct contact with the posterior periosteum of the humerus in most specimens. These anatomic relationships and findings add to the anatomical understanding of the radial nerve, which helps during operative approaches and fixation of the humerus.

Efficacy of a Virtual Arthroscopic Simulator for Orthopaedic Surgery Residents by Year in Training.

BACKGROUND: Virtual reality arthroscopic simulators are an attractive option for resident training and are increasingly used across training programs. However, no study has analyzed the utility of simulators for trainees based on their level of training/postgraduate year (PGY). PURPOSE/HYPOTHESIS: The primary aim of this study was to determine the utility of the ArthroS arthroscopic simulator for orthopaedic trainees based on their level of training. We hypothesized that residents at all levels would show similar improvements in performance after completion of the training modules. STUDY DESIGN: Descriptive laboratory study. METHODS: Eighteen orthopaedic surgery residents performed diagnostic knee and shoulder tasks on the ArthroS simulator. Participants completed a series of training modules and then repeated the diagnostic tasks. Correlation coefficients (r 2) were calculated for improvements in the mean composite score (based on the Imperial Global Arthroscopy Rating Scale [IGARS]) as a function of PGY. RESULTS: The mean improvement in the composite score for participants as a whole was 11.2 ± 10.0 points (P = .0003) for the knee simulator and 14.9 ± 10.9 points (P = .0352) for the shoulder simulator. When broken down by PGY, all groups showed improvement, with greater improvements seen for junior-level residents in the knee simulator and greater improvements seen for senior-level residents in the shoulder simulator. Analysis of variance for the score improvement variable among the different PGY groups yielded an f value of 1.640 (P = .2258) for the knee simulator data and an f value of 0.2292 (P = .917) for the shoulder simulator data. The correlation coefficient (r 2) was -0.866 for the knee score improvement and 0.887 for the shoulder score improvement. CONCLUSION: Residents training on a virtual arthroscopic simulator made significant improvements in both knee and shoulder arthroscopic surgery skills. CLINICAL RELEVANCE: The current study adds to mounting evidence supporting virtual arthroscopic simulator-based training for orthopaedic residents. Most significantly, this study also provides a baseline for evidence-based targeted use of arthroscopic simulators based on resident training level.

Management of distal humeral coronal shear fractures.

Coronal shear fractures of the distal humerus are rare, complex fractures that can be technically challenging to manage. They usually result from a low-energy fall and direct compression of the distal humerus by the radial head in a hyper-extended or semi-flexed elbow or from spontaneous reduction of a posterolateral subluxation or dislocation. Due to the small number of soft tissue attachments at this site, almost all of these fractures are displaced. The incidence of distal humeral coronal shear fractures is higher among women because of the higher rate of osteoporosis in women and the difference in carrying angle between men and women. Distal humeral coronal shear fractures may occur in isolation, may be part of a complex elbow injury, or may be associated with injuries proximal or distal to the elbow. An associated lateral collateral ligament injury is seen in up to 40% and an associated radial head fracture is seen in up to 30% of these fractures. Given the complex nature of distal humeral coronal shear fractures, there is preference for operative management. Operative fixation leads to stable anatomic reduction, restores articular congruity, and allows initiation of early range-of-motion movements in the majority of cases. Several surgical exposure and fixation techniques are available to reconstruct the articular surface following distal humeral coronal shear fractures. The lateral extensile approach and fixation with countersunk headless compression screws placed in an anterior-to-posterior fashion are commonly used. We have found a two-incision approach (direct anterior and lateral) that results in less soft tissue dissection and better outcomes than the lateral extensile approach in our experience. Stiffness, pain, articular incongruity, arthritis, and ulnohumeral instability may result if reduction is non-anatomic or if fixation fails.