Assessment of volar radiocarpal ligaments: MR arthrographic and arthroscopic correlation.

OBJECTIVE: The purpose of this study, with wrist arthroscopy as the reference standard, was to assess the usefulness of MRI in the detection of tears of the radioscaphocapitate and long radiolunate extrinsic carpal ligaments. MATERIALS AND METHODS: The cases of 26 patients consecutively registered from 2003 to 2009 who underwent wrist arthroscopy and wrist MR arthrography at our institution were identified. MR images were read by a musculoskeletal radiologist blinded to the arthroscopic findings. Operative reports and arthroscopic photographs were examined for descriptions of the radioscaphocapitate and long radiolunate ligaments. Ligaments were classified as intact or torn in all studies. With arthroscopy as the reference standard, sensitivity and specificity were calculated for both the radioscaphocapitate and the long radiolunate ligaments. RESULTS: Radioscaphocapitate and long radiolunate tears were diagnosed with MR arthrography in 50% and 31% of the 26 cases and arthroscopy in 31% and 31% of cases. With arthroscopy as the reference standard, the sensitivity of MR arthrography in the detection of radioscaphocapitate and long radiolunate tears was 63% and 25%; the specificity was 56% and 67%. CONCLUSION: With currently established imaging criteria, correlation between MR arthrographic and wrist arthroscopic findings in the assessment of tears of the radioscaphocapitate and long radiolunate ligaments is inconsistent. Because of the increasing clinical importance ascribed to the extrinsic carpal ligaments, further work aimed at refining both imaging techniques and diagnostic criteria in the MRI evaluation of these structures is warranted to improve correlation with results obtained at arthroscopy.

Rigid versus nonrigid occipitocervical fusion: a clinical comparison of short-term outcomes.

STUDY DESIGN: Retrospective data review. OBJECTIVE: To report clinical outcomes of both rigid and nonrigid occipitocervical (OC) fusion constructs of a multicenter cervical spine study group. BACKGROUND: The OC junction is susceptible to a wide variety of pathologic conditions that predispose it to instability. The need for arthodesis in symptomatic or neurologically unstable cases has led to the development of a variety of fusion techniques that can be classified as either nonrigid fixation techniques, such as sublaminar wiring or onlay bone grafting, or rigid internal fixation constructs, such as screws with plate or rods. Rigid fixation provides immediate stability and eliminates the need for external fixators, that is, halo-vest. Although a rigid construct would seem to confer several advantages over a nonrigid construct with external inmobilization supplementation, comparative clinical data are is lacking. METHODS: A clinical comparison of the rigid and the nonrigid forms of OC fusion was done retrospectively from the data of a multicenter cervical spine study group. A total of 71 occipitocervical fusion patients were identified: 25 with a nonrigid technique and 46 with a rigid construct. Average follow-up time was 6.3 months with a range of 1.5 to 36 for the rigid construct cohort and 15.7 months with a range of 1 to 36 months for the nonrigid cohort. Complications were recorded and correlated to the type of fixation and the type of external immobilization used. A χ analysis was done to evaluate the significant differences between complication rates of both the groups, that is, rigid and nonrigid constructs. RESULTS: Twenty-five nonrigidly fused patients had a complication rate of 48%, whereas 46 rigidly fused patients had a complication rate of 10% (P<0.01). Rigid forms of internal fixation for OC fusion has a significantly lower complication rate in short term. CONCLUSION: In addition to the many advantages of a rigid occipitocervical construct, the clinical complication rates are statistically significantly lower versus a nonrigidly fixed construct.

Biomechanical comparison of double-row locking plates versus single- and double-row non-locking plates in a comminuted metacarpal fracture model.

PURPOSE: Open or unstable metacarpal fractures frequently require open reduction and internal fixation. Locking plate technology has improved fixation of unstable fractures in certain settings. In this study, we hypothesized that there would be a difference in strength of fixation using double-row locking plates compared with single- and double-row non-locking plates in comminuted metacarpal fractures. METHODS: We tested our hypothesis in a gap metacarpal fracture model simulating comminution using fourth-generation, biomechanical testing-grade composite sawbones. The metacarpals were divided into 6 groups of 15 bones each. Groups 1 and 4 were plated with a standard 6-hole, 2.3-mm plate in AO fashion. Groups 2 and 5 were plated with a 6-hole double-row 3-dimensional non-locking plate with bicortical screws aimed for convergence. Groups 3 and 6 were plated with a 6-hole double-row 3-dimensional locking plate with unicortical screws. The plated metacarpals were then tested to failure against cantilever apex dorsal bending (groups 1-3) and torsion (groups 4-6). RESULTS: The loads to failure in groups 1 to 3 were 198 +/- 18, 223 +/- 29, and 203 +/- 19 N, respectively. The torques to failure in groups 4 to 6 were 2,033 +/- 155, 3,190 +/- 235, and 3,161 +/- 268 N mm, respectively. Group 2 had the highest load to failure, whereas groups 5 and 6 shared the highest torques to failure (p < .05). Locking and non-locking double-row plates had equivalent bending and torsional stiffness, significantly higher than observed for the single-row non-locking plate. No other statistical differences were noted between groups. CONCLUSIONS: When subjected to the physiologically relevant forces of apex dorsal bending and torsion in a comminuted metacarpal fracture model, double-row 3-dimensional non-locking plates provided superior stability in bending and equivalent stability in torsion compared with double-row 3-dimensional locking plates, whereas single-row non-locking plates provided the least stability.