William G. Hamilton

Changes in tibiotalar area of contact caused by lateral talar shift

A carbon black transference technique was used to determine the contact area in twenty-three dissected tibiotalar articulations, with the talus in neutral position and displaced one, two, four, and six millimeters laterally. The greatest reduction in contact area occurred during the initial one millimeter of lateral displacement, the average reduction being 42 per cent. With further lateral displacement of the talus the contact area was progressively reduced but the rate of change for each increment of shift was less marked.

THA With Delta Ceramic on Ceramic: Results of a Multicenter Investigational Device Exemption Trial

Although the published studies on the outcomes of total hip arthroplasty (THA) performed with currently available ceramic components show high survivorship and low bearing wear at midterm followup, concern over ceramic fracture and squeaking persist. For these reasons, the use of ceramic is limited. Recently, a new alumina matrix composite material (Delta ceramic) with improved material properties was developed to address these concerns. We report the early outcomes and complications of a prospective, randomized, multicenter trial of 263 patients (264 hips) at eight centers, comparing a Delta ceramic-on-ceramic (COC) articulation with a Delta ceramic head-crosslinked polyethylene bearing combination (COP). There were 177 COC hips and 87 COP hips. Complications were reported for all patients, whereas clinical and radiographic results were provided for the 233 patients with minimum 2-year followup (average, 31.2xa0months; range, 21–49xa0months). The Harris hip scores and clinical, radiographic, and survivorship outcomes were similar in both groups. There were four (2%) revisions in the COC group and two (2%) in the COP group. We encountered three intraoperative ceramic liner-related events. In addition, one patient receiving the COC underwent revision for chipping of the ceramic liner, and a second had ceramic fragmentation on followup radiographs but has not undergone revision. These liner related complications remain a concern. No patient reported squeaking in either group; this leaves us hopeful the new material will lessen the frequency of squeaking. In the short term, the Delta COC articulation provided similar functional scores and survivorship and complication rates with the ceramic head mated with crosslinked polyethylene.Level of Evidence: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

High Level of Residual Symptoms in Young Patients After Total Knee Arthroplasty

BackgroundTKA is among the fastest growing interventions in medicine, with procedure incidence increasing the most in younger patients. Global knee scores have a ceiling effect and do not capture the presence of difficulty or dissatisfaction with specific activities important to patients.Questions/purposesWe quantified the degree of residual symptoms and specific functional deficits in young patients who had undergone TKA.MethodsIn a national multicenter study, we quantified the degree of residual symptoms and specific functional deficits in 661 young patients (mean age, 54xa0years; range, 19–60xa0years; 61% female) at 1 to 4xa0years after primary TKA. To eliminate observer bias, satisfaction and function data were collected by an independent, third-party survey center with expertise in administering medical outcomes questionnaires for federal agencies.ResultsOverall, 89% of patients were satisfied with their ability to perform normal daily living activities, and 91% were satisfied with their pain relief. After TKA, 66% of patients indicated their knees felt normal, 33% reported some degree of pain, 41% reported stiffness, 33% reported grinding/other noises, 33% reported swelling/tightness, 38% reported difficulty getting in and out of a car, 31% reported difficulty getting in and out of a chair, and 54% reported difficulty with stairs. After recovery, 47% reported complete absence of a limp and 50% had participated in their most preferred sport or recreational activity in the past 30xa0days.ConclusionsWhen interviewed by an independent third party, about 1/3 of young patients reported residual symptoms and limitations after modern TKA. We recommend informing patients considering surgery about the high likelihood of residual symptoms and limitations after contemporary TKA, even when performed by experienced surgeons in high-volume centers, and taking specific steps to set patients’ expectations to a level that is likely to be met by the procedure as it now is performed.Level of EvidenceLevel III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Impact of Socioeconomic Factors on Outcome of Total Knee Arthroplasty

BackgroundFew data exist regarding the impact of socioeconomic factors on results of current TKA in young patients. Predictors of TKA outcomes have focused primarily on surgical technique, implant details, and individual patient clinical factors. The relative importance of these factors compared to patient socioeconomic status is not known.Questions/purposesWe determined whether (1) socioeconomic factors, (2) demographic factors, or (3) implant factors were associated with satisfaction and functional outcomes after TKA in young patients.MethodsWe surveyed 661 patients (average age, 54xa0years; range, 18–60xa0years; 61% female) 1 to 4xa0years after undergoing modern primary TKA for noninflammatory arthritis at five orthopaedic centers. Data were collected by an independent third party with expertise in collecting healthcare data for state and federal agencies. We examined specific questions regarding satisfaction, pain, and function after TKA and socioeconomic (household income, education, employment) and demographic (sex, minority status) factors. Multivariable analysis was conducted to examine the relative importance of these factors for each outcome of interest.ResultsPatients reporting incomes of less than USD 25,000 were less likely to be satisfied with TKA outcomes and more likely to have functional limitations after TKA than patients with higher incomes; no other socioeconomic factors were associated with satisfaction. Women were less likely to be satisfied and more likely to have functional limitations than men, and minority patients were more likely to have functional limitations than nonminority patients. Implants were not associated with outcomes after surgery.ConclusionsSocioeconomic factors, in particular low income, are more strongly associated with satisfaction and functional outcomes in young patients after TKA than demographic or implant factors. Future studies should be directed to determining the causes of this association, and studies of clinical results after TKA should consider stratifying patients by socioeconomic status.Level of EvidenceLevel III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Morbidity and Mortality in the Thirty-Day Period Following Total Hip Arthroplasty: Risk Factors and Incidence

The study sought to ascertain the incidence rates and risk factors for 30-day post-operative complications after primary total hip arthroplasty (THA). Complications were categorized as systemic or local and subcategorized as major or minor. There were 17,640 individuals who received primary THA identified from the 2006-2011 ACS NSQIP. The mortality rate was 0.35% and complications occurred in 4.9%. Age groups ≥ 80 years (P <0.001) and 70-79 years old (P = 0.003), and renal insufficiency (P = 0.02) best predicted mortality. Age ≥80 years (P <0.001) and cardiac disease (P = 0.01) were the strongest predictors of developing any postoperative complication. Morbid obesity (P <0.001) and operative time > 141 minutes (P <0.001) were strongly associated with the development of major local complications.

Learning Curve With Minimally Invasive Unicompartmental Knee Arthroplasty

This study examined 445 consecutive minimally invasive unicompartmental knee arthroplasties (UKAs) from one institution to determine whether revision and reoperation rates would decrease as the number of cases performed increased, indicating the presence of a learning curve with this procedure. At a mean of 3.25 years, 26 knees required revision yielding an overall revision rate of 5.8%; survivorship at 2 years with revision as an end point was 96% +/- 1.7%. Both revisions and reoperations decreased over time but not significantly. For the first half of UKA cases performed vs the second half, revision rates fell from 5.0% to 2.5%, and reoperation rates fell from 8.1% to 5.4%. These data demonstrate that despite modifications made to improve surgical technique across time, a substantial complication rate with this procedure persists.

Do Patients Return to Work After Total Knee Arthroplasty

BackgroundAlthough there is extensive literature supporting a high success rate, there are limited data on return to work after total knee arthroplasty (TKA).Questions/purposesWe sought to determine (1) the percentage of patients who returned to work after TKA; (2) what percentage returned to their original job; (3) whether this varied based on the physical job demand category; and (4) whether there were differences between men and women in terms of the likelihood of returning to work after TKA.MethodsA multicenter study was conducted of patients of working age (18–60xa0years) who underwent TKA 1 to 5xa0years previously. An independent third-party survey center with expertise in collecting healthcare data for state and federal agencies collected the data. Definitions from the US Department of Labor’s Dictionary of Occupational Titles were used to determine physical job demand categories of sedentary, light, medium, heavy, and very heavy. Complete data were collected on 661 patients undergoing TKA (average age 54xa0years, 61% women).ResultsSeventy-five percent (494 of 661) were employed in the 3xa0months before their TKA and 98% (482 of 494) returned to work after surgery; 89% (440 of 494) returned to the same job. Before surgery, physical demand categories of the patients’ jobs were sedentary 12%, light 10%, medium 24%, heavy 24%, and very heavy 30%. The return to work rate for those employed during the 3xa0months before surgery by physical demand category was sedentary 95%, light 91%, medium 100%, heavy 98%, and very heavy 97%. Men were more likely than women to have worked within the 3xa0months before TKA but there was no difference between sexes in return to work after TKA.ConclusionsIn this group of young patients, most returned to work at their usual occupation after TKA.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Femoral neck anteversion in ballerinas.

The elite ballet dancer has greater-than-average turnout, or external rotation, in the hip. Anatomic constraints, such as the angle of version of the femoral neck, or the femoral neck anteversion (FNA) angle, may limit the amount of external rotation or turnout in the hip. The purpose of this study was to determine whether dancers who have better-than-average turnout have lower-than-average FNA angles. Fourteen elite female dancers from three major American ballet companies were studied. The FNA angles were measured in 28 hips by magnetic resonance imaging techniques. The mean FNA angle in the dancers measured 11.9 degrees (range, 4 degrees-24 degrees), and was similar to the mean FNA angle in the general population (11.4 degrees). It was concluded that the average femoral neck anteversion angle in this select group of dancers is similar to that of the general population, although none of the dancers in this study had severe femoral neck anteversion.

Otto Aufranc Award: A Multicenter, Randomized Study of Outpatient versus Inpatient Total Hip Arthroplasty

BackgroundLength of stay after total hip arthroplasty (THA) has decreased over the last two decades. However, published studies that have examined same-day and early discharge protocols after THA have been done in highly selected patient groups operated on by senior surgeons in a nonrandomized fashion without control subjects.Questions/purposesThe purpose of this study was to evaluate and compare patients undergoing THA who are discharged on the same day as the surgery (“outpatient,” less than 12-hour stay) with those who are discharged after an overnight hospital stay (“inpatient”) with regard to the following outcomes: (1) postoperative pain; (2) perioperative complications and healthcare provider visits (readmission, emergency department or physician office); and (3) relative work effort for the surgeon’s office staff.MethodsA prospective, randomized study was conducted at two high-volume adult reconstruction centers between July 2014 and September 2015. Patients who were younger than 75xa0years of age at surgery, who could ambulate without a walker, who were not on chronic opioids, and whose body mass index was less than 40xa0kg/m2 were invited to participate. All patients had a primary THA performed by the direct anterior approach with spinal anesthesia at a hospital facility. Study data were evaluated using an intention-to-treat analysis. A total of 220 patients participated, of whom 112 were randomized to the outpatient group and 108 were randomized to the inpatient group. Of the 112 patients randomized to outpatient surgery, 85 (76%) were discharged as planned. Of the remaining 27 patients, 26 were discharged after one night in the hospital and one was discharged after two nights. Of the 108 patients randomized to inpatient surgery with an overnight hospital stay, 81 (75%) were discharged as planned. Of the remaining 27 patients, 18 met the discharge criteria on the day of their surgery and elected to leave the same day, whereas nine patients stayed two or more nights.ResultsOn the day of surgery, there was no difference in visual analog scale (VAS) pain among patients who were randomized to discharge on the same day and those who were randomized to remain in the hospital overnight (outpatient 2.8xa0±xa02.5, inpatient 3.3xa0±xa02.3, mean difference −0.5, 95% confidence interval [CI], −1.1 to 0.1, pxa0=xa00.12). On the first day after surgery, outpatients had higher VAS pain (at home) than inpatients (3.7xa0±xa02.3 versus 2.8xa0±xa02.1, mean difference 0.9, 95% CI, 0.3–1.5, pxa0=xa00.005). With the numbers available, there was no difference in the number of reoperations, hospital readmissions without reoperation, emergency department visits without hospital readmission, or acute office visits. At 4-week followup, there was no difference in the number of phone calls and emails with the surgeon’s office (outpatient: 2.4xa0±xa01.9, inpatient: 2.4xa0±xa02.2, mean difference 0, 95% CI, −0.5 to 0.6, pxa0=xa00.94).ConclusionsOutpatient THA can be implemented in a defined patient population without requiring additional work for the surgeon’s office. Because 24% (27 of 112) of patients planning to have outpatient surgery were not able to be discharged the same day, facilities to accommodate an overnight stay should be available.Level of EvidenceLevel I, therapeutic study.

Midterm Results of Delta Ceramic-on-Ceramic Total Hip Arthroplasty

This study reports mid-term results of Delta ceramic on ceramic (COC) in total hip arthroplasty (THA). Subjects received Delta COC THA in a prospective multi-center study with either 28 mm (n=177) or 36 mm (n=168) articulations. Annual clinical and radiographic evaluations were performed, and patients were asked about hip noises. At mean 5.3-year follow-up there were 3 (0.9%) post-operative liner fractures. Nine revisions were performed (2 liner fracture, 4 stem loosening, 3 deep infection). Kaplan-Meier survivorship at 6 years was 96.9% (94.0-98.4). Twenty-six (7.5%) subjects reported squeaking, of whom none were revised. One (0.3%) subject could reproduce a sound in clinic. More patients reported squeaking with a 36 mm bearing (28 mm: 7/177, 36 mm: 19/168, P=0.013).