Direct evidence of "damage accumulation" in cement mantles surrounding femoral hip stems retrieved at autopsy: cement damage correlates with duration of use and BMI.

The "damage accumulation" phenomenon has not been quantitatively demonstrated in clinical cement mantles surrounding femoral hip stems. We stained transverse sections of 11 postmortem retrieved femoral hip components fixed with cement using fluorescent dye-penetrant and quantified cement damage, voids, and cement-bone interface gaps in epifluorescence and white light micrographs. Crack density (Cr.Dn), crack length-density (Cr.Ln.Dn), porosity, and cement-bone interface gap fraction (c/b-gap%) were calculated, normalized by mantle area. Multiple regression tests showed that cement damage (Cr.Ln.Dn. & Cr.Dn.) was significantly positively correlated (r(2)=0.98, p<0.001) with "duration of use" and body mass index ("BMI") but not cement mantle "porosity". There were significant interactions: "duration of use"*"BMI" was strongly predictive (p<0.005) of Cr.Dn.; and "duration of use"*"porosity" was predictive (p=0.04) of Cr.Ln.Dn. Stem related cracks accounted for approximately one fifth of Cr.Dn and one third of Cr.Ln.Dn. The mean c/b-gap% was 13.8% but it did not correlate (r(2)=0.01, p=0.8) with duration of use. We concluded that duration-dependent fatigue damage accumulation occurred during in vivo use. BMI strongly influenced cement crack length and the rate of new crack formation over time. Voids did not increase the rate of crack initiation but appeared to have promoted crack growth over time. Although not progressive, substantial bone resorption at the cement-bone interface appeared to be common.

Femoral neuropathy following total hip arthroplasty. Anatomic study, case reports, and literature review.

Femoral neuropathy is an uncommon yet debilitating complication of total hip arthroplasty (THA). Over a 1-year period, in 440 consecutive THAs performed at Pennsylvania Hospital, 10 (2.3%) femoral neuropathies occurred. Among primary arthroplasties, all neuropathies were associated with the Hardinge anterolateral approach. A retrospective case review as well as a detailed anatomic cadaveric study highlighted the characteristics of the femoral nerve that make it susceptible to injury. In addition, a review of the existing literature on this subject was performed. Placement and management of acetabular retractors were the factors most commonly associated with injury of the femoral nerve. All affected patients had significant initial disability. However, full femoral nerve. All affected patients had significant initial disability. However, full functional recovery occurred within 1 postoperative year. Clear understanding and awareness of the anatomy of the femoral triangle as well as accurate placement of anterior acetabular retractors can minimize the incidence of this complication.

Compartment syndrome: a quantitative study of high-energy phosphorus compounds using 31P-magnetic resonance spectroscopy.

The purpose of this study was to quantitate the intracellular high-energy phosphate compounds during 6 hours of tissue ischemia in the anterior tibial compartment of beagles subjected to an induced traumatized compartment syndrome. The goal of this work was to provide clinicians with objective criteria to augment clinical judgment regarding surgical intervention in the impending compartment syndrome. A beagle model was utilized in which the Delta pressure (difference between the mean arterial pressure and compartment pressure) could be controlled. The model, in conjunction with 31P-magnetic resonance spectroscopy (MRS), allowed a measure of high-energy phosphate compounds and pH in the compartment at various Delta pressures. The extent of ischemic metabolic insult in the compartment was then quantitated. Our data suggest the following: 1) lower Delta pressures result in a proportionally greater drop in the intracellular phosphocreatine ratio and pH; 2) at lower Delta pressures, there is proportionally greater decline in the percentage recovery post-fasciotomy; 3) blood pressure is extremely important and periods of hypotension may result in increased muscle damage at lower compartment pressures.

Pelvic crush injuries with occlusion of the iliac artery.

During a 1-year period, three patients presented with acute traumatic thrombosis of the common or external iliac artery concomitant with a massive crush injury to the pelvis. All had vascular compromise of the involved extremity on initial physical examination, but in two patients with open pelvic trauma, exsanguination, major visceral injury, hypothermia, and a coagulopathy precluded emergency vascular reconstruction. Both required hindquarter amputation for adequate debridement. The third patient presented without exsanguination or visceral trauma. Angiography and vascular reconstruction were undertaken, but myonecrosis compounded the initial vascular compromise, and eventually required a hip disarticulation for debridement. It was concluded that: exsanguination and/or major visceral injury takes priority over emergency vascular reconstruction; soft-tissue injury may preclude limb salvage despite vascular reconstruction. If a cadaveric limb exists, early radical amputation, including hindquarter amputation, should be undertaken.