Background This study aimed to evaluate the early clinical outcomes of retrograde headless intramedullary screw fixation for displaced fifth metacarpal neck and shaft fractures. Methods We retrospectively reviewed nine patients treated with retrograde intramedullary screw fixation of fifth metacarpal neck and shaft fractures between 2011 and 2013. Patient demographics and outcomes including hand dominance, age, sex, type of injury, injury and postoperative radiographs, return to work, time to fracture union radiographically, complications, visual analog score, disabilities of the arm, shoulder, and hand scores, postoperative metacarpophalangeal joint range of motion, and grip strength were recorded. Results Nine fractures in nine patients with a mean age of 32 years (19-54) were included. There were seven metacarpal neck and two metacarpal shaft fractures. All patients sustained injury by direct impact of fist against an object. No case involved worker's compensation. Patients had a mean follow-up of 36 weeks (6-57 weeks) and at the time of latest follow-up had no pain. Mean radiographic healing was 49 days (28-85 days). Mean return to work was 6 weeks (4-10 weeks). Mean metacarpalphalangeal joint motion was 0°extension and 90°flexion. Mean disabilities of the arm, shoulder, and hand scores pre-and postoperatively improved from 43 to 0.7, respectively. The mean postoperative grip strength was measured of the injured hand (40 kg) and un-injured hand (41 kg). Conclusions Retrograde headless intramedullary screw fixation of fifth metacarpal neck and shaft fractures has overall favorable early outcomes and offers the benefit of stable fixation, early motion without cast immobilization, and the ability for early return to work. This technique is a viable surgical option for these fractures and may be considered in the appropriate patient population.

Prognostic level III. See Instructions for Authors for a complete description of levels of evidence.

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BackgroundMechanically replacing one or more pain generating articulations in the functional spinal unit (FSU) may be a motion preservation alternative to arthrodesis at the affected level. Baseline biomechanical data elucidating the quantity and quality of motion in such arthroplasty constructs is non-existent.PurposeThe purpose of the study was to quantify the motion-preserving effect of a posterior total disc replacement (PDR) combined with a unilateral facet replacement (FR) system at a single lumbar level (L4-L5). We hypothesized that reinforcement of the FSU with unilateral FR to replace the resected, native facet joint following PDR implantation would restore quality and quantity of motion and additionally not change biomechanics at the adjacent levels.Study DesignIn-vitro study using human cadaveric lumbar spines.MethodsSix (n = 6) cadaveric lumbar spines (L1-S1) were evaluated using a pure-moment stability testing protocol (±7.5 Nm) in flexion-extension (F/E), lateral bending (LB) and axial rotation (AR). Each specimen was tested in: (1) intact; (2) unilateral FR; and (3) unilateral FR + PDR conditions. Index and adjacent level ROM (using hybrid protocol) were determined opto-electronically. Interpedicular travel (IPT) and instantaneous center of rotation (ICR) at the index level were radiographically determined for each condition. ROM, ICR, and IPT measurements were compared (repeated measures ANOVA) between the three conditions.ResultsCompared to the intact spine, no significant changes in F/E, LB or AR ROM were identified as a result of unilateral FR or unilateral FR + PDR. No significant changes in adjacent L3-L4 or L5-S1 ROM were identified in any loading mode. No significant differences in IPT were identified between the three test conditions in F/E, LB or AR at the L4-L5 level. The ICRs qualitatively were similar for the intact and unilateral FR conditions and appeared to follow placement (along the anterior-posterior (AP) direction) of the PDR in the disc spaceConclusionBiomechanically, quantity and quality of motion are maintained with combined unilateral FR + PDR at a single lumbar spinal level.

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