Incidence of Distal Femoral Periprosthetic Fractures after Total Knee Arthroplasty.

BACKGROUND: The incidence of distal femoral periprosthetic fractures associated with total knee arthroplasty (TKA) has been reported as 0.3% to 2.5%. This study examined the incidence of distal femoral periprosthetic fractures at one hospital over a 16-year period. We hypothesized that the incidence of these fractures would be lowered after the introduction of lugged femoral implants and insertion of a distal femoral intramedullary bone graft during TKA. METHODS: From 1994 to 2010, 4,943 primary TKAs were performed. Following these TKA operations, 21 distal femoral fractures occurred. The surgical technique and implant design changed during this interval. Lugged femoral implants were introduced in 2000. Intramedullary bone grafting of the distal femoral intramedullary guide hole was introduced in 2002. RESULTS: The incidence of distal femoral periprosthetic fracture in this series of 4,943 TKA operations was 0.42% (21/4943). Six fractures occurred in 1,236 knees with femoral implants without femoral fixation lugs (0.49%). Fifteen fractures occurred in 3,707 knees with femoral implants with femoral fixation lugs (0.40%). Eight fractures occurred in 1,653 knees that did not have intramedullary bone grafts (0.48%). Thirteen fractures occurred in 3,290 knees that had intramedullary bone grafts (0.40%). Two fractures occurred in 417 knees with lugged femoral implants and no bone graft (0.48%). CONCLUSIONS: In this series, there was no significant difference in the incidence of distal femoral periprosthetic fractures associated with adding fixation lugs to the femoral implant and filling the femoral intramedullary hole with bone graft.

Polyethylene Liner Dissociation Is a Complication of the DePuy Pinnacle Cup: A Report of 23 Cases.

BACKGROUND: Polyethylene liner dissociation is a rare but catastrophic event in total hip arthroplasty (THA), and certain implant designs are known to be at greater risk. Although the DePuy Pinnacle (Warsaw, IN, USA) modular acetabular construct has an excellent record of fixation and wear, an unexpectedly high number of liner dissociations has been noted. QUESTIONS/PURPOSES: The purposes of this study were (1) to characterize the clinical parameters observed in a large group of patients who have experienced liner dissociations with the DePuy Pinnacle acetabular component; (2) to describe the radiographic findings in this group of patients; and (3) to calculate a minimum frequency of this complication. METHODS: Since 2001, 23 patients with previously well-functioning THAs presented with sudden atraumatic polyethylene liner dissociation at four separate institutions. These THAs were performed between 2001 and 2013. Eight different arthroplasty specialists had performed the index hip arthroplasties using the DePuy Pinnacle acetabular component with a polyethylene liner. Polyethylene failures were evaluated for liner type and radiographic cup position. For three of the surgeons who contributed cases, institutional registries allowed the calculation of the number of components of this type that they used during the period in question, which provided a conservative estimate of the frequency of this type of failure. RESULTS: All 23 liner failures occurred atraumatically in previously asymptomatic THAs at a mean of 48 months (range, 3-138 months). Patients characteristically reported a new and sudden onset of discomfort with audible, reproducible squeaking. Surgical inspection of dissociated liners demonstrated displacement of polyethylene with shearing of the peripheral locking tabs. Radiographic evaluation demonstrated that 14 cups were well positioned and nine cups were malpositioned outside the so-called safe zone. Conservative estimates of the frequency of this complication from the three surgeons' practices whose institutional registries allowed calculation of the lowest possible frequency were 0.32% (six of 1888), 0.77% (three of 391), and 0.82% (three of 367). CONCLUSIONS: With this report of 23 additional liner dissociations, we suggest that surgeons should be aware of the problem and take extra precautions when using this implant to ensure locking mechanism integrity at the time of surgery. We caution that the frequency of liner dissociation may be higher than previously reported. LEVEL OF EVIDENCE: Level IV, therapeutic study.

The Clinical and Economic Impact of Preoperative Transthoracic Echocardiography in Elderly Patients with Hip Fractures.

PURPOSE: The purpose of this study was to evaluate preoperative transthoracic echocardiography (TTE) on cardiac intervention, length of stay (LOS), inpatient mortality, and costs. METHODS: A retrospective series of 43 preoperative TTE and 161 non-TTE (control) hip fracture patients (> 65 years) was reviewed. The data collected included ASA score, comorbidities, indication for TTE, perioperative cardiac intervention, LOS, inpatient mortality, and cost. RESULTS: One of 43 (2.4%) (TTE) had a cardiac intervention (PTCA/CABG). Zero interventions occurred in the control group. The average time to operation was 1.5 days (TTE) and 0.93 days (control) (p < 0.001). The average LOS was 7.2 days (TTE) and 6.0 days (control), (p = 0.04). Patients (American Society of Anesthesiologists Physical Status Classification 3 and 4 patients), LOS was 7.3 days (TTE) and 6.3 days (control) (p = 0.18). Inpatient mortality was 2.3% (TTE) and 3% (control) (p = 0.493). There was no correlation between TTE and anesthesia. Hospital costs were different between groups (TTE $24,445 and control $18,429, p = 0.02). CONCLUSIONS: Preoperative TTE in elderly patients with hip fractures resulted in a low cardiac intervention rate. Patients undergoing preoperative TTE prior to surgery had longer times to operation, LOS, and higher hospital costs. The utility of TTE as a preoperative screening tool is limited in the geriatric hip fracture population and does not appear to effect perioperative mortality rates.

Diabetes mellitus, hemoglobin A1C, and the incidence of total joint arthroplasty infection.

Patients with diabetes have a higher incidence of infection after total joint arthroplasty (TJA) than patients without diabetes. Hemoglobin A1c (HbA1c) levels are a marker for blood glucose control in diabetic patients. A total of 3468 patients underwent 4241 primary or revision total hip arthroplasty or total knee arthroplasty at one institution. Hemoglobin A1c levels were examined to evaluate if there was a correlation between the control of HbA1c and infection after TJA. There were a total of 46 infections (28 deep and 18 superficial [9 cellulitis and 9 operative abscesses]). Twelve (3.43%) occurred in diabetic patients (n = 350; 8.3%) and 34 (0.87%) in nondiabetic patients (n = 3891; 91.7%) (P < .001). There were 9 deep (2.6%) infections in diabetic patients and 19 (0.49%) in nondiabetic patients. In noninfected, diabetic patients, HbA1c level ranged from 4.7% to 15.1% (mean, 6.92%). In infected diabetic patients, HbA1c level ranged from 5.1% to 11.7% (mean, 7.2%) (P < .445). The average HbA1c level in patients with diabetes was 6.93%. Diabetic patients have a significantly higher risk for infection after TJA. Hemoglobin A1c levels are not reliable for predicting the risk of infection after TJA.

Cementless acetabular fixation with and without screws: analysis of stability and migration.

The purpose of this study was to compare initial stability and late migration of 775 cementless acetabular components with and without screw fixation. Screw fixation was used in 509 cups and no screws in 266 cups. Average follow-up in the screw fixation group was 6.32 years (range, 2-10 years) and 6.9 years (range, 2-10 years) in the no-screw group. One component (0.2%, osteolysis) in the screw group and one (0.4%, loss of fixation) in the no-screw group required revision. Osteolytic lesions more than 4 cm(2) were noted in 8 (1.6%) screw fixation cups and 2 (0.75%) no-screw fixation cups. No cups in either cohort had radiographic evidence of migration. Screw fixation did not have a favorable or adverse effect on the outcome of acetabular reconstruction.

Prospective, randomized comparison of cobalt-chrome and titanium trilock femoral stems.

The purpose of this article was to demonstrate the efficacy of a cementless, flat, tapered wedge femoral stem and compare cobalt-chrome and titanium femoral stems with this design. Three hundred ninety femoral stems observed for a mean of 4.7 years (2.0-8.9 years) were prospectively evaluated with clinical and radiographic follow-up. Hips were stratified by Dorr classification, bone stock (femoral index), size of implant used, and material of femoral implant. Survivorship of the femoral stem at 8.9 years was 99.8% with no significant difference between cohorts. Thigh pain (4.9%) was more common with cobalt-chrome femoral stems (6.5%) than titanium femoral stems (3.1%). The flat, tapered wedge femoral stem design provides excellent femoral reconstruction in total hip arthroplasty. On the basis of this study, we use titanium femoral stems.

A comparison of acetate vs digital templating for preoperative planning of total hip arthroplasty: is digital templating accurate and safe?

The purposes of this study were to compare the accuracy of acetate and digital templating for primary total hip arthroplasty (THA) and to determine if digital templating is safe. Preoperative planning was performed on 50 consecutive preoperative radiographs during 2005. Templating results were compared with the actual hip implants used. Interrater reliability of acetate templating and accuracy of acetate and digital templating were recorded. Digital measurement overestimated acetabular size (P < .001) and underestimated the femoral size (P = .03). The absolute errors were larger for digital compared with acetate templating; however, mean absolute errors did not differ significantly (acetabulum, P = .090; femur, P = .114). Acetate and digital templating can accurately predict the size of THA implants. Digital templating was determined to be acceptably safe for preoperative planning of primary THA operations.

A comparison of acetate and digital templating for total knee arthroplasty.

UNLABELLED: Accurate preoperative templating can facilitate precise, efficient, and reproducible total knee arthroplasty. We determined whether acetate templating accurately predicted knee implants used and compared the accuracy of digital templating. Preoperative planning was performed on 50 consecutive preoperative radiographs during 2005. After digital images were obtained, appropriately magnified analog films were printed. Four arthroplasty surgeons and one resident performed acetate templating and one arthroplasty surgeon trained in the technique performed digital templating. Acetate and digital templating accurately predicted the size of the implanted component to within one size, 91% versus 93%, respectively. The digital technique was more accurate than acetate for tibial component size. Acetate and digital templating did not differ in predicting femoral component size. Our data suggest digital templating is at least as accurate as traditional acetate templating for predicting knee implant sizing. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

The effect of EPSTR and minimal incision surgery on dislocation after THA.

Dislocation rates after posterior approach THA have decreased with the advent of enhanced posterior soft tissue (EPSTR) repairs that incorporate the external rotators. We examined three posterior approaches (simple posterior repair, EPSTR, and posterior minimal incision surgery using enhanced posterior soft tissue repair) performed by one surgeon in 390 consecutive primary THA operations (390 patients) from 1992-2003. A simple posterior repair of the external rotators done through three drill holes was performed in the first 90 patients. EPSTR incorporating the external rotators and posterior capsule in one continuous sleeve was performed in 180 patients. A 10 cm mini incision with EPSTR was performed in 120 patients. The overall dislocation rate for the series was 2.3% (9 of 390 procedures) with a 1% (4 of 390 procedures) revision rate for dislocation. The simple repair group had a greater dislocation rate (5.5%) compared to the group with EPSTR (1.3%) and the minimal incision with EPSTR group (1.7%). EPSTR decreased dislocation after total hip arthroplasty performed with a posterior approach. A 10 cm mini incision posterior approach with EPSTR maintained the low dislocation rate. Revision rate for dislocation was equivalent between the 3 groups.