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Biomedical subjects

Rafael J Sierra

Publications and source records attributed to Rafael J Sierra.

10 recordsLinked to original sources
PubMed2007

Neurovascular injuries in acetabular reconstruction cage surgery: an anatomical study.

Acetabular reconstruction cages are indicated for severe combined segmental and cavitary acetabular bone defects. The purpose of this study was to evaluate the implications of screw placement and drill plunge and the potential insult to anatomical structures when implanting acetabular reconstruction cages. A segmental cavitary defect was reamed into the acetabulum and a cage was implanted in each of the 10 hemipelvises. The relative course of the superior gluteal neurovascular bundle was mapped to assess dissection intervals. When cage screws were placed at least 15 mm longer than needed, 13% and 20% of screws of the superior flange and anterior rim hit the femoral nerve, respectively, and approximately 60% of the screws placed in the posterior rim endangered the obturator nerve. A "safe zone" for screw size may be a 15- and 25-mm screw for the superior flange and posterior rim, respectively.

Acetabulum↗
PubMed2006

Dislocation of bipolar hemiarthroplasty: rate, contributing factors, and outcome.

UNLABELLED: Dislocation of bipolar hemiarthroplasty of the hip is a rare complication. The objectives of our study were to assess the incidence, contributing factors, and outcomes of bipolar prosthesis dislocation. From 1974 to 2001, 1812 primary bipolar hemiarthroplasties were done at our institution. Seventy-four percent were done in patients with fractures of the femoral neck. An anterolateral surgical approach was used in 79% of hips, a posterolateral approach was used in 14% of hips, and a transtrochanteric approach was used in 7% of hips. Thirty-two hips dislocated. The cumulative probabilities of dislocation at 1 year, 5 years, 10 years, and 20 years were 1.1% (95% CI range, 0.6%-1.6%), 1.5% (95% CI range, 0.9%-2.1%), 2.1% (95% CI range, 1.2%-3.1%), and 5% (95% CI range, 1.9%-9.6%), respectively. There was no significant association of dislocation with the surgical approach or with the primary operative diagnosis. More than (1/2) of the dislocations occurred within 6 months postoperative. Late dislocations occurred most commonly in patients with Bateman prostheses and osteonecrosis and were associated with inner bearing dissociation. Closed reduction was successful in preventing additional surgery in only 30% of patients. The surgeon must be aware that closed reduction may be unsuccessful, and open reduction with replacement of components may be necessary. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Adolescent↗
PubMed2005

Revision total knees done for extensor problems frequently require reoperation.

UNLABELLED: We retrospectively reviewed 361 patients who had a revision total knee arthroplasty done for an extensor mechanism problem to assess the prevalence, etiology, and risk factors for subsequent reoperation. The prevalence of reoperation was 23% because 84 patients were reoperated on one or more times. The average time to the first reoperation was 2.4 years. The total number of reoperations was 127 with 58 patients reoperated on once, 15 reoperated on twice, and 11 reoperated on three or more times. The cumulative risk of a reoperation for any reason after index revision was 7% at 1 year, 19.6% at 5 years, and 35.9% at 10 years. The most common reason for reoperation was a new or recurrent patellofemoral problem, which accounted for 33% of the first reoperations. The risk of reoperation was substantially lower for patients that had femoral or tibial component malrotation corrected at the time of revision TKA. The risk of reoperation after revision TKA for an extensor mechanism complication increased in patients operated on in the 1990s compared with patients operated on in the 1970s and 1980s. LEVEL OF EVIDENCE: Therapeutic study, Level-IV-1 (case series). See the Guidelines for authors for a complete description of levels of evidence.

Arthroplasty, Replacement, Knee↗
PubMed2005

Dislocation of primary THA done through a posterolateral approach in the elderly.

UNLABELLED: We assess the rate of dislocation of total hip arthroplasty (THA) through a posterolateral approach in elderly patients and determine if this complication can be minimized. We retrospectively reviewed 150 THAs done between 1992 and 2002, through a posterolateral approach in patients 80 years and older. A hybrid THA was done in 46% of patients and both components were cemented in 54% of patients. A 28-mm head was used in 83% of the patients and a 32-mm head was used in 17% of patients. An elevated liner, with the elevation placed posteriorly, was used in 38% of hybrid cases. Starting in mid-1998, the posterior capsule was preserved and repaired at the time of wound closure (n = 77, 51%). Dislocation occurred in eight hips (five recurrent) at an average time to dislocation of 26.9 months (range, 1-79 months). No dislocations occurred when using a 32-mm head or a 28-mm head with a lipped liner in association with repair of the posterior capsule. Statistical regression analysis indicated that capsular repair was the single most important predictive factor for dislocation. When using the posterolateral approach for THA in patients older than 80 years, we suggest using a 32-mm head in combination with posterior capsular repair to reduce the incidence of dislocation. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (retrospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.

Aged, 80 and over↗
PubMed2005

Dislocation rate after hip hemiarthroplasty in patients with tumor-related conditions.

BACKGROUND: Hemiarthroplasty is frequently used to treat femoral neck insufficiency resulting from neoplastic disease in the proximal part of the femur. The authors of a recent study analyzed the dislocation rates following hemiarthroplasty but excluded patients with tumor involvement of the site of the surgery as they hypothesized that the dislocation rates would be markedly higher in such patients. The current study was performed to compare the dislocation rate following hemiarthroplasties performed in patients without tumor involvement with the rate following hemiarthroplasties in patients with tumor involvement of the surgical site. METHODS: Patients who had undergone hemiarthroplasty following resection of a tumor involving the proximal part of the femur were identified in a total joint registry, and the patients' charts were reviewed retrospectively to determine dislocation rates, preoperative conditions, and postoperative outcomes and treatments. Between 1974 and 2001, 1812 patients were treated with hemiarthroplasty for reasons other than tumor involvement and 320 hemiarthroplasties were performed because of tumor-related conditions. The patients who were treated for a tumor-related condition were younger, and a higher proportion of them were men. RESULTS: The ten-year dislocation rate after the hemiarthroplasties performed for tumor-related conditions (10.9%) was higher than that following the hemiarthroplasties performed for non-tumor-related conditions (2.1%) (p = 0.002). The median time to dislocation in the patients with a tumor-related condition (twenty-four days) was shorter than that for the patients without tumor involvement (thirty-seven days). Preservation of the greater trochanter in patients with tumor involvement did not have a significant influence on the dislocation rate, but it showed a favorable trend toward decreasing that rate (hazard ratio = 3.5, p = 0.06). CONCLUSIONS: The short-term and long-term dislocation rates associated with hemiarthroplasties performed for a tumor-related condition at the site of the surgery were significantly higher than those associated with hemiarthroplasties performed for reasons other than tumor involvement. Preservation of the greater trochanter showed a trend toward decreasing the likelihood of dislocation following the hemiarthroplasty, and it was more influential than the level of resection and the extent of soft-tissue compromise. We think that preservation of the greater trochanter should be attempted when it is justifiable according to the principles of oncologic surgery.

Adolescent↗
PubMed2004

Race, ethnicity, insurance coverage, and preoperative status of hip and knee surgical patients.

Our objective was to examine the association between race/ethnicity and insurance type and the preoperative status of patients undergoing joint arthroplasty surgery. Quality of life and WOMAC measures were collected preoperatively in a consecutive series of patients undergoing primary hip or knee arthroplasties (n = 573). Non-Hispanic whites had lower preoperative pain and WOMAC scores and higher Quality Well Being Index and SF-36 scores compared with other racial/ethnic subgroups. Patients with Medicare/private insurance had better preoperative scores relative to patients with Medicaid or no insurance. Racial/ethnic status was generally more strongly associated with preoperative status than was insurance type. Hispanics, blacks, and patients without Medicare or private health insurance reach arthroplasty surgery with lower preoperative functional and health status.

Arthroplasty, Replacement, Hip↗
PubMed2004

Reoperations after 3200 revision TKAs: rates, etiology, and lessons learned.

The purpose of this study was to evaluate the prevalence, etiology, and evolution with time of reoperations done after index revision total knee arthroplasties. After exclusion criteria were met, 1814 index knee revisions in 1627 patients were included in the final cohort with more than 50% of the revisions done for loosening and extensor mechanism problems and more than 80% of the revisions involving the femoral, tibial, or both components. Three hundred seventy-three knees subsequently have been reoperated on one or more times. The average time from index revision total knee arthroplasty to the first reoperation was 3.5 years (range, 1 day-19 years). Of the 1814 index revision total knee arthroplasties, 373 (20%) had 593 reoperations in 336 patients. The cumulative risks of first reoperation at 5, 10, and 15 years were 16.1% (95% CI, 14.2, 17.9), 26% (95% CI, 23.4, 28.6), and 31.4% (95% CI, 30.2, 39), respectively. There was no difference in risk to first reoperation when comparing the decades in which the index revisions were done (1970-1980, 1981-1990, and 1991-2000). There was a trend toward a higher cumulative risk of first time reoperations for deep infection, loosening, and instability in the last decade, but with the numbers available this was not statistically significant. The prevalence of reoperations in this large series of index revision total knee arthroplasties done for aseptic reasons was surprisingly high. Despite substantial improvements during the past 3 decades in component design, surgical technique, and prevention of infection, patients who have a revision total knee arthroplasty are at substantial risk of having one or more subsequent problems that result in a reoperation.

Arthroplasty, Replacement, Knee↗
PubMed2003

Above-the-knee amputation after a total knee replacement: prevalence, etiology, and functional outcome.

BACKGROUND: Despite modern surgical techniques, salvage of a failed total knee replacement remains a challenge. In certain situations, when other treatment options have been exhausted, patients with a failed total knee replacement may become candidates for above-the-knee amputation. The objective of this study was to assess the prevalence, etiology, and functional outcome of above-the-knee amputation performed proximal to an ipsilateral total knee replacement. METHODS: From 1970 to 2000, 18,443 primary total knee replacements were performed at our institution; sixty-seven (0.36%) were eventually followed by above-the-knee amputation. Forty-two of the amputations were performed for a cause unrelated to the total knee replacement, most commonly peripheral vascular disease (twenty-four knees). The remaining twenty-five above-the-knee amputations were performed for causes related to the total knee replacement: nineteen were done for uncontrollable infection; two, for periprosthetic fracture; two, for pain; one, for severe bone loss; and one, for a vascular complication. RESULTS: The twenty-five above-the-knee amputations performed for causes related to the total knee replacement were done at an average of 8.6 years (range, eight days to 23.6 years) after the replacement. The prevalence of above-the-knee amputations done for causes related to total knee replacement was 0.14%. Complications after the above-the-knee amputation included deep infection in five patients and superficial infection and skin necrosis in one each; there was also one perioperative death. Nine of the twenty-five limbs were fitted with an above-the-knee prosthesis, but only five patients were walking even to a limited degree with the prosthesis at the time of the last follow-up. CONCLUSIONS: The overall prevalence of amputation after total knee arthroplasty at our tertiary care center was 0.36%. The majority (63%) of the amputations were performed for reasons not attributable to complications of the arthroplasty. The functional outcome after amputation performed above a total knee replacement is poor. A substantial percentage of the patients were never fitted with a prosthesis, and those who were seldom obtained functional independence.

Aged↗
PubMed2002

Conversion of failed hip hemiarthroplasties after femoral neck fractures.

Hemiarthroplasty has been the preferred treatment for fractures of the femoral neck in elderly patients. The objective of the current study was to assess the outcome of revision of failed hemiarthroplasty to total hip arthroplasty in patients with a primary diagnosis of a femoral neck fracture. One hundred thirty-two conversions were done in 108 women and 24 men. One hundred two cemented and 30 uncemented hemiprostheses were revised to 88 cemented, 17 uncemented, and 27 hybrid total hip arthroplasties and the patients were followed up an average of 7.1 years (range, 5.1-15.3 years). Nine hips (6.8%) were revised for loosening and four additional hips (3%) were loose at the last followup. Survivorship free of revision was 96.5% (95% confidence interval, 93%-100%) at 5 years and 92% (95% confidence interval, 86%-98%) at 10 years. Major perioperative complications occurred frequently (45%), including 12 intraoperative femoral fractures (9%) and 13 dislocations (9.8%) Three of 12 (25%) of the intraoperative femoral fractures developed later femoral component loosening and all occurred during conversion of an uncemented Austin-Moore type hemiprosthesis. Conversion of endoprostheses to total hip arthroplasties after femoral neck fractures is fraught with high complication and loosening rates. Careful patient selection for each type of arthroplasty (hemiarthroplasty versus total hip arthroplasty) may help ameliorate the outcome of arthroplasty for patients with femoral neck fractures.

Age Factors↗