Abstract
The effects of orthopedic implants are typically evaluated clinically through reports of patient pain and studies on functional outcomes. From a forensic anthropological perspective, research on orthopedic implants is limited to their efficacy in human identification. Absent from both contexts is an investigation into how these implants may affect bones as a response to changes in biomechanical loading and gait. The identification of a pattern of expected changes to weight-bearing bones will better inform clinicians on expected outcomes and assist anthropologists in distinguishing these changes from those alterations which are due to other pathological conditions or age-related changes.
This exploratory study specifically evaluates the pattern of pathological changes observed on the spine, pelvis, and lower extremities in human skeletal remains presenting with an orthopedic implant in the lower extremity. I focus on the observations of antemortem fracturing, aberrant facets, Schmorl’s nodes, osteochondritis dissecans, heterotopic ossification, and osteoarthritic severity in various locations on the lumbar spine, ossa coxae, femora, patellae, tibiae, fibulae, tali, and calcanei. Measures of leg length discrepancy between antimeres were also collected as differences in leg length caused by implants may contribute to the pathologic change. These observations were compared to those of a commensurable group of skeletal remains of similar age and sex distribution, though lacking an orthopedic implant, to assure the validity of the findings as attributable to the presence of an orthopedic implant. Using donated skeletal remains from the FGCU HITA donated skeletal collection and the UTK forensic dentistry collection, I examined the relationship between pathology, osteoarthritic severity, leg length discrepancy, and implant presence.
Consistent with published data, the Mann-Whitney U test found a difference in the distributions of leg length across implant presence. Indicating that more severe manifestations of leg length discrepancy (<1cm) were found most often in those with an implant. Interestingly, there was a difference in the distribution of osteochondritis dissecans across implant presence and severe leg length discrepancies. The control sample presented with significantly more manifestations, which was expected as OD is a severe manifestation of OA and removed during degenerative joint replacement arthroscopies. Though other tests of significance were attempted, the small sample size precluded effective statistical analysis. Notwithstanding, the visual evaluation of histograms found that the relationship between antemortem fracturing and implant presence is trending toward significance. Similarly, severe (grade “3”) osteoarthritis was observed more often in the sample with implants as compared to those without. All bones, with the exception of the femora and L4 vertebrae, were affected by pathology more often in the sample with an implant present. No significant findings were discovered between pathology and implant type, sex, or age. The findings of this study indicate the need for future research which expands upon the relationship between antemortem fracturing and severe osteoarthritis in remains which present with an orthopedic implant.