Simultaneous prosthetic joint infection of ipsilateral hip and knee arthroplasties is often accompanied by significant bone loss and presents a challenging reconstructive problem. Two-stage reconstruction is favored and requires the placement of a total femur spacer, which is not a commercially available device. We describe a surgical technique, reporting on 2 cases in which a customized total femur antibiotic impregnated spacer was created by combining an articulating knee spacer and an articulating hip spacer with a reinforced cement dowel construct connecting the 2 spacers. Custom total femoral spacers are useful in the management of infected femoral megaprostheses and cases with ipsilateral injected hip and knee arthroplasties and severe femoral bone loss.
Atraumatic hip instability is an increasingly recognized source of pain and hip dysfunction. It can result from numerous causes, including femoroacetabular impingement, prior trauma, injury to the capsuloligamentous structures, and idiopathic etiologies. Occult hip instability can be a challenging diagnosis that requires careful attention to, and interpretation of, history, physical examination, and radiographic imaging findings. Iatrogenic hip instability is a potential complication of both open and arthroscopic hip-preserving surgical procedures that can have catastrophic results. Atraumatic hip instability is a pathologic entity that can be successfully addressed with open and arthroscopic procedures.
To develop a nondestructive method of measuring distal radioulnar joint (DRUJ) joint reaction force (JRF) that preserves all periarticular soft tissues and more accurately reflects in vivo conditions.
Eight fresh-frozen human cadaveric limbs were obtained. A threaded Steinmann pin was placed in the middle of the lateral side of the distal radius transverse to the DRUJ. A second pin was placed into the middle of the medial side of the distal ulna colinear to the distal radial pin. Specimens were mounted onto a tensile testing machine using a custom fixture. A uniaxial distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Force-displacement curves were generated and a best-fit polynomial was solved to determine JRF.
All force-displacement curves demonstrated an initial high slope where relatively large forces were required to distract the joint. This ended with an inflection point followed by a linear area with a low slope, where small increases in force generated larger amounts of distraction. Each sample was measured 3 times and there was high reproducibility between repeated measurements. The average baseline DRUJ JRF was 7.5 N (n = 8).
This study describes a reproducible method of measuring DRUJ reaction forces that preserves all periarticular stabilizing structures. This technique of JRF measurement may also be suited for applications in the small joints of the wrist and hand.
Changes in JRF can alter native joint mechanics and lead to pathology. Reliable methods of measuring these forces are important for determining how pathology and surgical interventions affect joint biomechanics.
To compare how ulnar diaphyseal shortening and wafer resection affect distal radioulnar joint (DRUJ) joint reaction force (JRF) using a nondestructive method of measurement. Our hypothesis was that ulnar shortening osteotomy would increase DRUJ JRF more than wafer resection.
Eight fresh-frozen human cadaveric upper limbs were obtained. Under fluoroscopic guidance, a threaded pin was inserted into the lateral radius orthogonal to the DRUJ and a second pin was placed in the medial ulna coaxial to the radial pin. Each limb was mounted onto a mechanical tensile testing machine and a distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Data sets were entered into a computer and a polynomial was generated and solved to determine the JRF. This process was repeated after ulnar diaphyseal osteotomy, ulnar re-lengthening, and ulnar wafer resection. The JRF was compared among the 4 conditions.
Average baseline DRUJ JRF for the 8 arms increased significantly after diaphyseal ulnar shortening osteotomy (7.2 vs 10.3 N). Average JRF after re-lengthening the ulna and wafer resection was 6.9 and 6.7 N, respectively. There were no differences in JRF among baseline, relengthened, and wafer resection conditions.
Distal radioulnar joint JRF increased significantly after ulnar diaphyseal shortening osteotomy and did not increase after ulnar wafer resection.
Diaphyseal ulnar shortening osteotomy increases DRUJ JRF, which may lead to DRUJ arthrosis.
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