Faculty Bibliography

Surgical fixation is generally the treatment used for the repair of uncomplicated fractures of the hip. However, complications following the fixation of such fractures, such as nonunion, hardware failure, osteonecrosis, posttraumatic osteoarthritis, and infection may require salvage treatment with total hip arthroplasty. This systematic review article addresses the challenges of conversion to total hip arthroplasty after prior fixation of a hip fracture, and provides recommendations for minimizing complications related to such conversion

In this study, we compare patients' risk-taking and spending behaviors to their willingness to pay (WTP) for novel implants in a joint arthroplasty. 210 patients were surveyed regarding risk-taking and spending behavior, and WTP for novel implants with either increased-longevity, increased-longevity with higher risk of complications, or decreased risk of complications compared to a standard implant. Patients with increased recreational risk-taking behavior were more WTP for increased-longevity. Patients who "rarely" take health-risks were more WTP for decreased risk of complications. Patients with higher combined risk scores were more WTP for all novel implants. Patients who paid more than $50,000 for their current car were more WTP for decreased complications. This study shows that patients' risk taking and spending behavior influences their WTP for novel implants.

BACKGROUND: Modular metal-backed tibia components allow surgeons intraoperative flexibility. Although it is known that modular tibia components introduce the possibility for backside wear resulting from relative motion between the polyethylene insert and the tibial baseplate, it is not known to what degree variability in the conformity of the tibial polyethylene liner itself might contribute to backside wear. QUESTIONS/PURPOSES: The purpose of this study was to determine whether a flat, cruciate-retaining tibial polyethylene bearing generates less backside wear than a more conforming (curved) tibial polyethylene bearing in an analysis of specimens explanted during revision surgery. METHODS: The study included 70 total knee inserts explanted at revision surgery, all implanted and explanted by the same surgeon. Two different cruciate-retaining insert options in an otherwise similar knee system were used: one with a curved-on-flat (17) articular geometry and one with a highly conforming curved-on-curved design (53); both groups were sequential cohorts. The composite backside wear depth for the insert as well as the volume of backside wear was measured and compared between groups. RESULTS: The median linear backside-normalized wear for the posterior lipped inserts was 0.0063 mm/year (range, 0-0.085 mm/year), which was lower than for the curved inserts at 0.05 mm/year (range, 0.00003-0.14 mm/year) (p<0.001). The median calculated volumetric backside-normalized wear for the posterior lipped inserts was 14.2 mm3/year (range, 0-282.8 mm3/year) compared with 117 mm3/year (range, 2.1-312 mm3/year) for the curved inserts (p<0.001). CONCLUSIONS: In this retrieval study, more conforming tibial inserts demonstrated more backside-normalized wear than the flatter designs. This suggests that in this modular total knee arthroplasty design, higher articular conformity to address the issues of high bearing contact stress comes at a price: increased torque transmitted to the backside insert-to-tray interface. We suggest further work be undertaken to examine newer insert designs to evaluate if our conclusions hold true with the newer generation locking mechanism, tibial tray finish and polyethylene designs, as more highly conforming tibial inserts are introduced into the market. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The purpose of this study was to determine the percentage of patients discharged with a subtherapeutic INR <1.8 using our institutions inpatient warfarin dosing nomogram following total joint arthroplasty (TJA). We examined predisposing risk factors for a subtherapeutic discharge (INR <1.8), including increased body weight, age, gender, end stage renal disease (ESRD), smoking, and peri-operative transfusion. Chart review identified 249 patients for study inclusion. Logistic regression (LR) was used to identify associated risk factors for a subtherapeutic INR (<1.8) on day of discharge. The majority of patients (58.6%, 146 of 249) following TJA surgery were found to have a subtherapeutic INR level (INR<1.8) at discharge (mean length of stay 2.6 days). Multivariate LR analysis found that weight greater than 180 lbs. (OR 2.08, CI 1.09, 3.98, P=0.027) was found to increase the odds of a subtherapeutic INR on day of discharge. Our results were not significant for weight 20% beyond ideal body weight, age (>65y), gender, peri-operative transfusion, smoking, ESRD or autoimmune disease. A patient's body weight influences response to warfarin following TJA. An inpatient warfarin dosing nomogram that takes into account a patient's weight should be used to reduce the risk of subtherapeutic INR levels in obese TJA patients.

INTRODUCTION: Real-time monitoring of blood loss is critical in fluid management. Visual estimation remains the standard of care in estimating blood loss, yet is demonstrably inaccurate. Photometric analysis, which is the referenced "gold-standard" for measuring blood loss, is both time-consuming and costly. The purpose of this study was to evaluate the efficacy of a novel tablet-monitoring device for measurement of Hb loss during orthopaedic procedures. METHODS: This is a prospective study of 50 patients in a consecutive series of joint arthroplasty cases. The novel System with Feature Extraction Technology was used to measure the amount of Hb contained within surgical sponges intra-operatively. The system's measures were then compared with those obtained via gravimetric method and photometric analysis. Accuracy was evaluated using linear regression and Bland-Altman analysis. RESULTS: Our results showed a significant positive correlation between Triton tablet system and photometric analysis with respect to intra-operative hemoglobin and blood loss at 0.92 and 0.91, respectively. DISCUSSION: This novel system can accurately determine Hb loss contained within surgical sponges. We believe that this user-friendly software can be used for measurement of total intraoperative blood loss and thus aid in a more accurate fluid management protocols during orthopaedic surgical procedures.

BACKGROUND: Determining the cause of synovitis following total knee arthroplasty (TKA) can be challenging. The differential diagnoses include infection, hemarthrosis, instability, crystalline disease, wear debris or idiopathic causes. Wear particle synovitis can mimic periprosthetic infection with symptoms of pain and effusion. Radiographs and physical exam are often inconclusive in differentiating the two. Synovial fluid analysis is routinely used in evaluating periprosthetic infections. We examined the association between synovial white blood cell count and differentials, and polyethylene wear and osteolysis, to see if fluid analysis can aid in establishing the diagnosis of wear particle synovitis. METHODS: A cell count and differential was obtained from synovial fluid samples from 54 TKAs undergoing revision for aseptic failure. Explanted polyethylene inserts were analyzed for linear and volumetric wear, oxidation (ketone peak height), and damage features. Analysis was performed to assess the relationship between cell counts and polyethylene wear indicators as well as severity of intra-operative and radiographic osteolysis. RESULTS: Total and percent mononuclear (monocyte and lymphocyte) cell counts were found to be elevated in the presence of documented wear debris synovitis and an association was suggested between their levels and maximum ketone levels. CONCLUSION: The present study implies that the differential cell count of knee fluid can help distinguish wear debris from infection as a source of synovitis following TKA and identifies the value of the mononuclear cell count as a possible tool to assess abnormal wear rates of the polyethylene insert. Further research into identifying the exact role of monocytes in the wear debris synovitis and osteolytic pathways is warranted. LEVEL OF EVIDENCE: Level II, diagnostic study.

The geometry of the intercondylar box plays a significant role in the development of patellar clunk syndrome. We reviewed the incidence of patella clunk at mid-to-long-term follow-up of a rotating high-flex versus fixed bearing posterior stabilized TKA design. 188-mobile and 223-fixed bearing TKAs were reviewed for complications, incidence of patellar clunk, treatment, recurrence rates, range of motion, and patient satisfaction. Patellar clunk developed in 22 knees in the mobile (11.7%) and in 4 (1.8%) in the fixed bearing group (P<0.001). 23 out of 26 cases resolved with a single arthroscopic treatment and 2 resolved with a second procedure. The mean postoperative range of motion was 122.4 degrees . All but one patient reported overall satisfaction with the index procedure. In contrast with other recent studies we found a significant incidence of patellar clunk in high-flex mobile bearings. Despite the high rate of patellar clunk syndrome, overall patients did well and were satisfied with their outcomes.

Length of stay (LOS) after total joint arthroplasty (TJA) impacts the expense to the hospital. Our purpose was to evaluate the impact that day of surgery has on postoperative LOS. 547 patients who had a primary TJA at two tertiary care hospitals were identified retrospectively. TJA patients admitted on day of surgery and who had primary elective surgery were included in our sample. Patients were subdivided into one of four groups: those who had operations on Monday, Tuesday, Thursday, and Friday respectively. Patients who had surgery on Thursday and Friday had significantly longer LOS when compared to Monday and Tuesday. This variation in LOS between the groups may be due to inconsistencies in weekend functionality, less experienced part-time staffing, and inaccessibility of rehabilitation personnel.

This study investigated the impact of metabolic syndrome (MetS) on perioperative and postoperative complication rates: the results of a cohort of 168 total hip and knee arthroplasties, 63 of normal weight, 105 with obesity without risk factors for metabolic syndrome and 39 with obesity and other factors that classify them with metabolic syndrome. Patients with metabolic syndrome were more likely to have complications than those without metabolic syndrome (P=0.0156). Perioperative and postoperative complication rates for the MetS and control groups were 35.9% and 16.3%, respectively. Elevated BMI was the element of MetS that had the largest impact on post-surgical complication rates, and this was statistically significant (P=0.0028). The presence of MetS in patients undergoing total joint arthroplasty has a significant impact on surgical complication rates. This cannot be attributed to the BMI component alone, and may help guide efforts of patient optimization prior to total joint arthroplasty.

As health care organizations adapt to more accountable financial models, it is increasingly important to assess how patients value new technologies, and their willingness to contribute to their cost. A questionnaire described features of a 'standard' implant including its longevity and risk of complications. We asked if participants would be willing to contribute to the cost of 3 novel implants with differing longevity and risk of complications. Our cohort included 195 patients, 45% were willing to add a co-pay to increase the longevity. Willingness to pay decreased to 26% with increased risk of complications, and 29% were willing to pay for a decreased risk of complications. Patients with higher education level, private insurance and males were more willing to contribute for a novel prosthesis. This study demonstrated that 26%-45% of patients are willing to share costs of a novel prosthesis. Willingness to pay was associated with the proposed implant benefits and with patient characteristics.