Biomedical subjects

Harry B Skinner

Publications and source records attributed to Harry B Skinner.

8 recordsLinked to original sources

PubMed2006

Feasibility of a percutaneous technique for repairing proximal femora with simulated metastatic lesions.

Fracture of the proximal femur due to metastatic disease is a significant cause of morbidity and mortality among breast cancer patients. Prophylactic surgical fixation is advised for patients at risk of fracture and typically involves placement of an orthopaedic implant. We propose that some proximal femora with metastases can be repaired by removing the lesion and filling the resulting defect with bone cement (polymethylmethacrylate), a procedure that could be performed percutaneously without the use of hardware. We studied the strengths of 12 matched pairs of cadaveric proximal femora under single-limb stance loading. One femur from each pair remained intact, while a simulated metastatic lesion, measuring approximately 75% of the neck diameter, was burred into the neck of the contralateral femur. The defects were repaired using a procedure similar to the one proposed. Femoral strength was measured via mechanical testing to failure. The strengths of the repaired femora averaged 94.7% of the strength of their respective contralateral intact femur (standard deviation, 8.7%). These findings suggest that the proposed procedure may be useful for some patients with metastases in the femoral neck. If the proximal femur could be safely repaired using the proposed technique in place of conventional surgical fixation, the patient would benefit from a shorter and less invasive surgical procedure, less pain and discomfort, greatly reduced recovery time, and a shorter hospital stay-all at a much lower cost.

Aged↗

PubMed2006

The effect of the "mini" incision in total hip arthroplasty on component position.

This study compares cemented and uncemented total hip arthroplasties performed through either a standard or mini incision. The parameters evaluated were dislocation rates, Gruen and DeLee zones, Barrack cement grading, component positioning, and heterotopic bone levels. There were no statistically significant differences found between the mini and standard incision groups except in 2 parameters. Analysis of femoral stems not in neutral position revealed statistically significant differences between cemented and uncemented stems. The mean anteversion of the mini incision cup was also significantly less than the standard group, although probably not clinically significant. In conclusion, the mini incision does not compromise total hip arthroplasty results on the acetabular side, but varus positioning of the cemented femoral component nearing 2 degrees is concerning for the long-term success of these arthroplasties.

Acetabulum↗

PubMed2005

Predicting proximal femoral strength using structural engineering models.

Hip fracture related to osteoporosis and metastatic disease is a major cause of morbidity and mortality. An accurate and precise method of predicting proximal femoral strength and fracture location would be useful for research and clinical studies of hip fracture. The goals of this study were to develop a structural modeling technique that accurately predicts proximal femoral strength; to evaluate the accuracy and precision of this predicted strength on an independent data set; and to evaluate the ability of this technique to predict fracture location. Fresh human cadaveric proximal femora with and without metastatic lesions were studied using computed tomography scan-based three-dimensional structural models and mechanical testing to failure under single-limb stance-type loading. The models understated proximal femoral strength by an average of 444 N, and the precision of the predicted strength was +/- 1900 N. Therefore, the ability to predict hip strength in an individual subject is limited primarily by the level of precision, rather than accuracy. This level of precision is likely to be sufficient for many studies of hip strength. Finally, these models predict fractures involving the subcapital and cervical regions, consistent with most fractures produced experimentally under single-limb stance-type loading.

Aged↗

PubMed2005

Predicting the strength of femoral shafts with and without metastatic lesions.

To evaluate a potential tool for assessing the risk of a pathologic fracture of the femoral shaft, we examined whether fracture loads computed by our computed tomography scan-based finite element models are predictive of measured fracture loads. We also evaluated whether the precision of the computed fracture loads for shafts with metastases is altered if models are generated using mechanical property-density relationships for bone without metastases. We investigated whether femoral shafts with a hemispheric defect and shafts with metastases have qualitatively similar structural behavior. Using identical four-point bending loading conditions, we computed and measured fracture loads of femoral shafts with and without metastases and with a burred hemispheric defect to simulate a tumor. Finite element model fracture loads were strongly predictive of the measured fracture loads (range, 0.92-0.98) even when the models of bones with metastases used mechanical property relationships for bone without metastases. Specimens with hemispheric defects behaved structurally differently than specimens with metastases, indicating that these defects do not accurately simulate the effects of metastases. Results of our study show that these computed tomography scan-based finite element models can be used to estimate the strength of femoral shafts with and without metastases. These models may be useful for assessing the risk of pathologic fractures of femoral shafts.

Aged↗

PubMed2004

Concerns about ceramics in THA.

Currently available ceramic materials are superior to those used originally in total hip arthroplasty, which should translate into a much lower complication rate than what has been reported previously. In spite of this, a number of concerns remain. The ceramic-on-ceramic articulation is not immune to wear and surface damage. Conditions associated with ceramic wear include vertical cup position, femoral neck impingement, and femoral head separation. A unique pattern of stripe wear has been described as something that results from microseparation during gait. Catastrophic failure, although rare, continues to be a concern, and not all fractures can be predicted by proof testing. Revisions needed because of ceramic fractures can be extensive, and the results of the revision procedures can be compromised by the presence of highly abrasive particulate debris that is retained. Other concerns include the generation of debris from modular interfaces, neck damage and debris generation from impingement of some designs, inability to use a ceramic head a second time on a metal trunnion, and the dramatic loss of head and liner options intraoperatively. Although ceramics show great promise as a lower wear articulation, manufacturing and design modifications and improvements will continue in an attempt to address the substantial concerns that persist.

Ceramics↗

PubMed2004

Results of a multimodal analgesic trial involving patients with total hip or total knee arthroplasty.

The mainstays for pain relief after total hip arthroplasty (THA) and total knee arthroplasty (TKA) have been the opioids, but these medications, though excellent analgesics, have problems limiting their effectiveness. Alternative analgesics have been considered too mild for the pain caused by THA and TKA. These medications have been used in combination, but only in pairs and not in a "stacked modality." Here we report a trial of around-the-clock acetaminophen, rofecoxib, tramadol, and dexamethasone combined with bupivicaine pain pumps and on-demand opioid use (patient-controlled analgesia with morphine). Patients (48 with THA, 54 with TKA) were divided into pain protocol (PP) groups and conventional pain-therapy groups. Important variables were recorded from a chart review. In the PP groups, reductions in opioid use, length of hospital stay (TKA, P=.012), and time on patient-controlled analgesia were significant, as were improvements in pain scores for TKA. In addition, there was a trend in improved pain scores for the PP group with THA. Minor adverse events were similar for the groups, but major medical complications were fewer in the PP group. Preemptive analgesia with multiple non-narcotic medications used in a stacked modality can significantly reduce postoperative pain.

Acetaminophen↗

PubMed2004

Multimodal acute pain management.

Unrelieved postoperative pain following arthroplasty has been shown to delay patients' recovery and discharge from the hospital. Undertreatment of acute pain may also result in greater use of healthcare resources and ultimately lead to poor outcomes. This article reviews a multimodal approach to reduce pain at each step of the pain nocioception process by combining various analgesics that each operate through a different site or mechanism of action, allowing the physician to tailor the regimen to the patient. A therapeutic combination of analgesics (eg, opioids, nonsteroidal anti-inflammatory drugs, and bupivicaine) can provide adequate pain relief; however, regional anesthesia is fraught with side effects. The use of multimodal analgesia reduces hospital stay, decreases medical complications, and increases patient satisfaction.

Analgesia, Epidural↗

PubMed2002

Clinical implications of thromboprophylaxis in the management of total hip and knee arthroplasty.

Thrombosis is the most common cause of mortality in the United States, resulting in more than 2 million deaths per year. Almost an equal number of individuals are affected each year by nonfatal thrombosis, including deep vein thrombosis and nonfatal pulmonary embolism. A large proportion of thrombotic episodes can be prevented by the appropriate selection of prophylactic therapy--a clinical decision that figures greatly in numerous clinical conditions associated with an increased risk of thrombosis, including major orthopedic surgery. Orthopedic surgeons are well aware of the risks for complications inherent in total hip arthroplasty and total knee arthroplasty in particular. However, determining which protocols are optimal for thromboprophylaxis remains a matter of contention, and the choice of prophylactic therapy is a critical factor in the successful completion of any major orthopedic surgical procedure. Although there are key differences between total hip and knee arthroplasty in terms of the measures available for thromboprophylaxis and the data documenting their relative degree of effectiveness, the two procedures share many similarities in these respects as well as in their surgical protocols. By reviewing the data and practice guidelines on thromboprophylaxis in total hip and knee arthroplasty together, orthopedic surgeons can more clearly see the implications for clinical success that the choice of prophylactic therapy has on their management of these two vitally important procedures.

Anticoagulants↗