Antegrade Fixation of Distal Metaphyseal Ulnar Shortening Osteotomy

The ulnar shortening osteotomy (USO) is a common procedure used to treat ulnar impaction syndrome secondary to static or dynamic ulnar-positive variance. There are many described techniques for the USO. The distal metaphyseal ulnar shortening osteotomy (DMUSO) with retrograde cannulated screw fixation was described to reduce complications seen with other techniques. Biomechanical analysis of fixation constructs demonstrates 2-screw constructs are significantly stiffer than 1 screw and antegrade constructs have similar or greater stiffness when compared with retrograde constructs. Here, we describe a technique of antegrade cannulated screw fixation for DMUSO that obviates the need for the disruption of the distal radioulnar joint for intra-articular exposure of the ulnar head. Similar to the traditional retrograde DMUSO technique, this construct may also decrease the risk of delayed union, symptomatic implants associated with diaphyseal osteotomies, and disruption of triangular fibrocartilaginous complex in wafer procedures.

Distal Metaphyseal Ulnar Shortening Osteotomy Fixation: A Biomechanical Analysis

PURPOSE

Ulnar shortening osteotomy can be used to treat ulnar impaction syndrome and other causes of ulnar wrist pain. Distal metaphyseal ulnar shortening osteotomy (DMUSO) is one technique that has been proposed to reduce the complications seen with a diaphyseal USO or a wafer resection. However, to our knowledge, the optimal fixation construct for DMUSO has not been studied. We sought to characterize the biomechanical stiffness and rotational stability of different DMUSO constructs.

METHODS

A DMUSO was performed on 40 human cadaveric ulnas using 4 different fixation constructs (10 specimens per group): one 3.0 mm antegrade screw; two 2.2 mm antegrade screws; one 3.0 mm retrograde screw; and two 2.2 mm retrograde screws. Biaxial testing using axial load and cyclical axial torque was performed until failure, defined as 10° of rotation or 2 mm displacement. Specimens were assessed for stiffness at failure. Bone density was assessed using the second metacarpal cortical percentage.

RESULTS

Bone density was similar between all 4 testing groups. Of the 4 groups, the 2 antegrade screw group exhibited the highest rotational stiffness of 232 ± 102 Nm/deg. In paired analysis, this was significantly greater than 1 retrograde screw constructs. In multivariable analysis, 2-screw constructs were significantly stiffer than 1 screw and antegrade constructs were significantly stiffer than retrograde. Maximum failure torque did not differ with orientation, but 2 screws failed at significantly higher torques.

CONCLUSION

Using 2 screws for DMUSO fixation constructs may provide higher stiffness and maximum failure torque, and antegrade screw constructs may provide more stiffness than retrograde constructs.

CLINICAL RELEVANCE

Antegrade screw fixation using 2 screws may provide the strongest construct for DMUSO. Antegrade fixation may be preferred because it avoids violating the distal radioulnar joint capsule and articular surface of the ulna.

Low profile fragment specific plate fixation of lateral tibial plateau fractures - A technical note

PURPOSE

Precontoured plates used to stabilize lateral tibial plateau (LTP) fractures are limited in their ability to raft particular areas of the reconstructed articular surface. These implants also do not fit every individual's bony anatomy and can lead to soft tissue irritation. The purpose of this study was to evaluate fragment specific plate fixation of LTP fractures using generic small and mini fragment constructs.

METHODS

This was a retrospective case series of LTP fractures treated with small fragment tubular and/or mini fragment plate constructs at a single Level I trauma center. Postoperative complications were recorded. Final radiographs were analyzed to determine union and interval subsidence of the articular surface and/or loss of reduction.

RESULTS

All 19 LTP fractures healed without loss of reduction or implant failure. There was minimal interval subsidence of the LTP in all patients. There were no complications or reoperations for symptomatic implant removal within the given follow-up period.

CONCLUSION

Fragment specific fixation of LTP fractures using small and mini fragment plates creates a lower profile construct that reliably maintains fracture reduction to union.

Trochanteric osteotomy for acetabular fracture fixation: a case series and literature review

PURPOSE

This study examined osteotomy union and heterotopic ossification (HO) after performing digastric trochanteric osteotomies during open reduction and internal fixation (ORIF) of acetabular and combined femoral head fractures. Femoral head osteonecrosis and trochanteric screw removal were secondarily assessed.

METHODS

Twenty-six patients treated at a Level I trauma center, from years 2003 to 2019, who received a digastric trochanteric osteotomy during acetabular and combined femoral head fracture ORIF through a posterior surgical approach were retrospectively identified. Osteotomies were fixed with two 3.5 mm cortical lag screws. Rates of osteotomy union, HO, femoral head osteonecrosis, and trochanteric screw removal were determined.

RESULTS

All osteotomies went onto union without displacement or failure of fixation. Only three (12%) patients developed severe HO (modified-Brooker class III-IV). There were no instances of femoral head osteonecrosis and only one (7%) patient required trochanteric screw removal.

CONCLUSIONS

The digastric trochanteric osteotomy heals reliably with low rates of severe HO, femoral head osteonecrosis, and screw removal for soft-tissue irritation. A review of the literature is presented and found comparable findings.

Mammogram interpretation by physician assistants

The objective of this study was to determine whether a health maintenance organization (HMO) desirous of providing low-cost, quality mammography could employ physician assistants (PAs) to interpret mammograms under the supervision of HMO radiologists. After intensive training in mammographic interpretation, four PAs individually interpreted 727 mammograms of 470 normal breasts, 75 breasts with benign breast masses, and 182 breasts with cancer. The interpretations by the PAs were more sensitive and as specific as those made by six HMO radiologists who interpreted the same cases, and as effective as those by radiologists described in the literature. In receiver-operating-characteristic curve analysis, the areas under curves for PAs were larger than those under curves for radiologists. Interpretations by PAs took less time and cost less than did those by radiologists; the dispositions recommended by PAs were similar to those recommended by radiologists. We conclude that properly trained, evaluated, and supervised PAs can interpret mammograms. Legal, practical, and ethical considerations dictate that this can best be accomplished under the direction of radiologists who are well trained in mammography.

Spinal cord injury: time out of bed during rehabilitation

Preliminary experience in applying unobtrusive instrumentation to monitor selected patient activities over extended periods of time has shown this procedure to be both feasible and useful. The target activity studied was time out of bed (TOB) for 36 spinal cord injury patients undergoing comprehensive rehabilitation. Measurements were made with a rest-time monitor (RTM), which provides an objective daily record of how often and for how long a patient is out of bed. During the initial week of mobilization, paraplegic patients (n = 14) were out of bed for an average of 1.7 hours and quadriplegic patients (n = 22) for an average of 1.5 hours. Maximum TOB in each group was 8.7 and 9.2 hours, respectively, which dropped to 7.2 and 7.8 hours at time of discharge. Based on this experience, a standard activity curve has been developed which is used as a reference in assessing the weekly progress of individual patients. Distinctive types of activity patterns are described in relation to clinical and functional outcomes during hospitalization and 12 months after discharge.