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.

Survivorship and Complications of Revision Total Hip Arthroplasty with a Mid-Modular Femoral Stem.

We retrospectively reviewed 161 revision THAs with diaphyseal fitting, mid-modular femoral components performed by ten surgeons at two academic medical centers. The average follow-up was 6.1 years. At final follow-up, 4 patients required re-revision for failure of the femoral component; 3 (2%) for aseptic loosening and 1 for mechanical failure of stem in setting of periprosthetic fracture. There were a total of 24 (14.9%) revisions for any reason, with the most common reason being septic failure (10 of 24). To our knowledge, this is the largest reported series of mid-term survivorship and complications of revision THA with mid-modular femoral components. Our results show that these stems have a low rate of aseptic loosening, subsidence, and mechanical failure.

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.

Complications of femoral nerve block for total knee arthroplasty.

UNLABELLED: Preemptive and multimodal pain control protocols have been introduced to enhance rehabilitation after total knee arthroplasty (TKA). We determined the complication rate associated with preoperative femoral nerve block (FNB) for TKA. Among 1018 TKA operations, we performed 709 FNBs using a single-injection technique into the femoral nerve sheath and confirming position with nerve stimulation before induction. After TKA, weightbearing as tolerated was initiated using a walker or crutches on postoperative Day 1. Twelve patients (1.6%) treated with FNB sustained falls, three (0.4%) of whom underwent reoperations. Five patients had postoperative femoral neuritis, which may have been secondary to the block. One patient had new onset of atrial fibrillation after FNB, and the TKA was postponed. Femoral nerve block before TKA is not a harmless intervention. We recommend postoperative protocols be modified for patients who have FNB to account for decreased quadriceps function in the early postoperative period, which can lead to falls. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

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.

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 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.

The John Charnley Award: heritable thrombophilia and development of thromboembolic disease after total hip arthroplasty.

UNLABELLED: We retrospectively assessed whether heritable thrombophilia-hypofibrinolysis was more common in patients developing venous thromboembolism after total hip replacement than among control patients who did not develop venous thromboembolism, as an approach to better identify causes of venous thromboembolism after total hip arthroplasty. Twenty patients with proximal deep venous thrombosis after THA and 23 patients with symptomatic pulmonary embolism were compared with 43 control patients who did not have postoperative venous thromboembolism. Five of 42 patients with venous thromboembolism (12%) and 0 of 43 control patients (0%) had antithrombin III deficiency (< 75%). Nine of 42 patients with venous thromboembolism (21%) and 2 of 43 control patients (4.7%) had protein C deficiency (< 70%). Ten of 43 patients with venous thromboembolism (9 heterozygous, 1 homozygous; 23%) and 1 of 43 control patients (heterozygous; 2%) had the prothrombin gene mutation. Patients who had venous thromboembolism after total hip arthroplasty were more likely than matched control patients to have heritable thrombophilia with antithrombin III or protein C deficiency, or homo-heterozygosity for the prothrombin gene mutation. Screening for these three tests of heritable thrombophilia before total hip arthroplasty should improve the identification of patients with a reduced risk of venous thromboembolism who may need only mild thromboprophylaxis, and of those patients with heritable thrombophilia in whom prophylaxis should be more aggressive. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (lesser-quality RCT). See the Guidelines for Authors for a complete description of levels of evidence.

Heterotopic ossification of the quadriceps following distal femoral traction: a report of three cases and a review of the literature.

SUMMARY: We present the previously unreported complication of symptomatic heterotopic ossification of the quadriceps following placement of a large-diameter Steinmann pin for the purpose of temporary skeletal traction. Following the development of distal quadriceps heterotopic bone formation in three patients, we conducted a comprehensive search of the literature using the Medline database from 1966 to the present. A variety of publications, including review articles, case reports, and randomized prospective studies, were used for the literature review. This potential complication should be considered when using a large-diameter Steinmann pin in the distal femur for skeletal traction.