Radiographic morphometry and densitometry predict strength of cadaveric proximal humeri more reliably than age and DXA scan density

Methods are needed for identifying poorer quality cadaver proximal humeri to ensure that they are not disproportionately segregated into experimental groups for fracture studies. We hypothesized that measurements made from radiographs of cadaveric proximal humeri are stronger predictors of fracture strength than chronological age or bone density values derived from dual-energy x-ray absorptiometry (DXA) scans. Thirty-three proximal humeri (range: 39-78 years) were analyzed for: (1) bone mineral density (BMD, g/cm(2)) using DXA, (2) bulk density (g/cm(3)) using DXA and volume displacement, (3) regional bone density in millimeters of aluminum (mmAl) using radiographs, and (4) regional mean (medial+lateral) cortical thickness and cortical index (CI) using radiographs. The bones were then fractured simulating a fall. Strongest correlations with ultimate fracture load (UFL) were: mean cortical thickness at two diaphyseal locations (r = 0.71; p < 0.001), and mean mmAl in the humeral head (r = 0.70; p < 0.001). Weaker correlations were found between UFL and DXA-BMD (r = 0.60), bulk density (r = 0.43), CI (r = 0.61), and age (r = -0.65) (p values <0.01). Analyses between UFL and the product of any two characteristics showed six combinations with r-values >0.80, but none included DXA-derived density, CI, or age. Radiographic morphometric and densitometric measurements from radiographs are therefore stronger predictors of UFL than age, CI, or DXA-derived density measurements.

A novel double-row rotator cuff repair exceeds strengths of conventional repairs

Double-row rotator cuff repairs are becoming popular because of their ability to improve initial ultimate failure load for full-thickness rotator cuff tears, especially in middle-aged to elderly patients. We hypothesized a quasi-double-row repair using a combination of transosseous sutures, anchors, and double knots (TOAK technique) would exceed the clinically relevant 250-N load threshold and the initial mean ultimate failure loads of anchor-only and transosseous suture-only fixation. In simulated full-thickness supraspinatus tears in cadavers (mean age, 62 years; range, 50-77 years), failure loads of two repair techniques were compared with a TOAK repair using sutures and bioabsorbable anchors. Radiographic densitometry was conducted on all humeral heads. Testing was performed at 6 mm per minute in 18 bones in the following three groups (n = 6 per group): (1) transosseous suture-only with weave-type stitch and single-knot fixation; (2) anchor-only with horizontal mattress stitch and single-knot fixation; and (3) TOAK. The mean ultimate failure load was 238 N for the transosseous suture-only group and 215 N for the anchor-only group. Although the bones had lower density, TOAK specimens failed at 55% to 67% higher loads (mean, 404 N) than the other groups. These data support further evaluation of the TOAK technique for full-thickness supraspinatus tears in middle-aged to elderly patients.

Risks of radiation exposure to orthopaedic surgeons

The risks of occupational radiation exposure for orthopaedic surgeons has not been well documented. The use of fluoroscopy in orthopaedics has reduced morbidity and by reducing operative time and by reducing the invasiveness of procedures. Increasingly procedures requiring the use of fluoroscopy are being developed. In a prospective study we have monitored cumulative radiation exposure over a 6-month period. The exposure levels are well below the maximum dose limits for ionizing radiation as recommended by European Economic Communities EURATOM directives. Experimentally using a phantom patient it was shown that the exposure to ionizing radiation during the insertion of a dynamic hip screw was minimal. Despite the low level of exposure care should be exercised when using fluoroscopy.

Giant ganglion of the proximal tibiofibular joint: a case report

Ganglions of the tibiofibular joint are a rare condition. The exact tissue of origin could not be accurately determined despite the use of CAT scanning. At surgery a giant ganglion of the tibiofibular joint was resected with preservation of the peroneal nerve.

Extensor tendon sheath stenosis resulting in triggering of the little finger

An isolated constriction of the tendon sheath of extensor digiti minimi caused triggering of the little finger. Incision of the tendon sheath resulted in recovery of frictionless gliding of the tendon.

Fracture dislocation of the fifth metacarpal resulting in compression of the deep branch of the ulnar nerve

A volar fracture dislocation of the base of the fifth metacarpal resulted in compression of the deep branch of the ulnar nerve. Operative correction of the deformity resulted in full recovery.

Phase equilibria in the system ZnCl2 + KI

Phase equilibria in the ZnCl2+KI system have been investigated by differential thermal analysis (DTA), and by examination by X-ray powder diffraction of solidified melts. The system evidently behaves as a simple binary, and three congruently melting compounds are formed, viz. 2KI.ZnCl2, 2KI.3ZnCl2 and KI.4ZnC12. Supercooled mixtures from c. 60-90 mole % ZnCl2 visibly phase separate at temperatures for the most part about 30K below the liquidus temperatures, and the phase separation temperatures have been determined by DTA. The composition limits of the metastable immiscibility dome have not been established, but the region of phase separation extends at least to mixtures containing as little as 53 mole % ZnCl2. The critical composition is approximately 80 mole % ZnCl2, and the critical temperature 470 K. Quenching of melts containing 34-100 mole % ZnCl2, in liquid nitrogen, yields glasses. In the region 34-43 mole % ZnCl2 the glasses are partly crystallized. Glass transition temperatures for the wholly glassy mixtures have been evaluated from DTA traces, with heating rates in the range 0.11-0.25 K s-1. Two glass transitions have been observed for mixtures of composition 53-75 mole % ZnCl2.

Traumatic fracture of contact lens with corneal injury

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