Biomechanical Comparison between Volar Plate Fixator and Nonbridge External Wrist Fixator.

Intra-articular distal radius fractures are difficult to reduce and maintain by nonoperative means. ORIF leaves implants in the patient long after the fracture is healed. External fixation can stabilize the reduced fracture and leaves no long-term implants. The nonbridging fixator (NBX) will provide better reduction and comparable rigidity of fixation to a volar plate for a 5-fragment, OTA 23 C3.2 distal radius fracture. A 5-part distal radius fracture was created in 5 pairs of cadaver arms. One arm was randomly fixed with the NBX fixator; the matched pair was fixed with a volar plate (VPS). Fluoroscopic images recorded the extremes of passive volar-dorsiflexion range of motion (ROM) and radial-ulnar deviation ROM. Each arm was loaded with an axial force at a constant displacement rate until failure. The average reduction of radial tilt achieved for the NBX group was 13.8 ± 4.8° and 6.3 ± 4.7° for VPS; radial length: 3.4 ± 3.7 mm for NBX and 1.9 ± 1.0 mm for VPS; volar tilt: 26.3 ± 12.4° for NBX and 14.0 ± 13.5° for VPS. For NBX, ROM was slightly less after fixation than before fracture. ROM with volar plating was greater after fracture. The peak axial load for NBX was 925 ± 445 N; for VPS, 2,152 ± 1023 N. NBX had minimal effect on ROM and provided adequate strength and restoration of alignment at least as good as VPS for this 5-part fracture model.

Treatment of Selected Distal Radius Fractures with Nonbridging External Fixation.

A nonbridging external fixation (NBX) system with 1.6-mm diameter pins provided excellent stability for distal radius fractures in cadavers. For the present study, all patients with distal radius fractures were seen by the surgeon authors. Fractures that were displaced and unstable, including Orthopaedic Trauma Association (OTA) types 23-A2.3 to C3.3, were reduced and fixed with the NBX system. The Western Institutional Review Board granted approval (296864) for this retrospective study. Fractures numbered five OTA-A2, eight OTA-A3, two OTA-B3, one OTA-C1, two OTA-C2, and eight OTA-C3. In total, the study included 26 patients. At fixator removal, average dorsiflexion was 37.0° ± 17.8°; volar flexion, 39.4° ± 17.2°; pronation, 80.6° ± 16.1°; and supination, 48.1° ± 24.2°. Follow-up averaged 11.7 mo ± 19.2 mo. At final follow-up, average dorsiflexion was 52.9° ± 25.0°; volar flexion, 53.1° ± 23.7°; pronation, 80.8° ± 14.5°; and supination, 67.7° ± 30.3°. Average radial tilt at the time of injury was 11.6° ± 8.3°; post op to 23.9° ± 5.0°; and at last follow-up, 23.1° ± 5.0°. Average radial styloid length at the time of injury was 4.1 mm ± 3.7 mm; post op to 11.4 mm ± 3.0 mm; and at last follow-up, 10.5 mm ± 3.1 mm. Volar tilt at the time of injury averaged -19.6° ± 14.8°; reduced to 9.8° ± 6.3°; and at last follow-up, 7.5° ± 6.5°. This form of nonbridging fixation is safe and effective at maintaining reduced, extra- and intra-articular, distal radius fractures and allows functional range of motion with minimal complications.

The parathyroid gland in health and disease.

The authors studied the parathyroid glands from 100 previously healthy subjects who died suddenly and were admitted to the Dade County Medical Examiner's (ME) morgue and from 66 inpatients who died at Jackson Memorial Hospital (JMH). Parathyroid glands in patients with diseases (JMH series) were heavier than those in healthy persons (ME series), and both groups of glands were significantly heavier than those previously reported. Mean glandular weight in white subjects was 42.6 +/- 20.3 mg, with a range of 22-103 mg. The 95% upper limit of gland weight for healthy white subjects was 73.1 mg and for black subjects, 91.6 mg. The size and weight exhibited a skewed distribution. Gland weight varied with age, increasing to a maximum in the 41-60 year old age group in all subsets except white women, in whom it continued to increase till after age 70. There was slight correlation (r2 = 0.15) of gland weight with body weight within series and race groups; parenchymal content of the glands was not constant but correlated positively with glandular weight. Glands from both series had a comparable fat content. Fat was unevenly distributed throughout the gland, and its amount was highly variable, ranging between 0 and 90%, with a mean of 26% for white subjects and 24% for black subjects in both series. Therefore, percentage fat may not be used as an index of hyperplasia. Healthy back subjects had heavier glands than healthy white subjects, unaccounted for by differences in body weights; this difference was not statistically significant in subjects with disease. Within the black race, glands were not significantly heavier in disease than in health, and in the few cases with serum calcium determinations, the gland weight did not vary inversely with serum calcium levels as in white subjects, suggesting a basic difference in parathyroid calcium metabolism between the two races.