Steven N. Copp

Portable Compression Device and Low-Molecular-Weight Heparin Compared With Low-Molecular-Weight Heparin for Thromboprophylaxis After Total Joint Arthroplasty

This preliminary prospective study to determine the rate of deep venous thrombosis (DVT) examined 277 patients undergoing total knee or total hip arthroplasty (TKA or THA) who were randomized to use a portable, continuous enhanced circulation therapy (CECT) compression device and low-molecular-weight heparin (LMWH) or to receive LMWH alone. Patients were screened for DVT using duplex ultrasound at hospital discharge and followed clinically for 3 months. In TKA, 5 DVTs (6.6%) occurred in the CECT + LMWH group compared with one pulmonary embolism and 14 DVTs (19.5%) in the LMWH group (P = .018). In THA, 1 DVT (1.5%) occurred in the CECT + LMWH group and 2 DVTs (3.4%) occurred in the LMWH group. This preliminary study demonstrated significant reduction in rate of DVT after TKA when the CECT device was combined with LMWH.

Extensor Mechanism Function in Single-Radius Vs Multiradius Femoral Components for Total Knee Arthroplasty

The early outcomes of 2 newer-generation posterior cruciate ligament-retaining fixed-bearing total knee arthroplasty (TKA) implant designs were assessed to determine if a single sagittal radius femoral design has an advantage in obtaining earlier knee range of motion and function when compared with a contemporary multiradius femoral design. Total knee arthroplasty patients were prospectively randomized to receive either a single sagittal radius femoral design (n=50) or a multiradius femoral design (n=50). Knee extensor mechanism function after TKA with either a single sagittal radius or multiradius implant was comparable in contemporary posterior cruciate ligament-retaining TKA designs.

Accuracy of A Handheld Accelerometer-Based Navigation System for Femoral and Tibial Resection in Total Knee Arthroplasty

Restoration of mechanical axis in total knee arthroplasty (TKA) is correlated with improved implant survivorship. We assessed the accuracy and required surgical time using a hand-held accelerometer-based navigation system for TKA. Data collected on 53 patients included assembly, resection, and tourniquet times. Implant alignment and mechanical axis were measured on radiographs. Femoral alignment was 0.29° ± 2.2° varus. Tibial alignment was 0.09° ± 1.4° valgus. Postoperative mechanical axis was 0.2° ± 2.1° varus. Malalignment rates for the femur, tibia, and axis were 13%, 3.8%, and 17%, respectively. Average time for pinning and navigating was 3.6 minutes for the femur and 2.6 minutes for the tibia; mean tourniquet time was 62 minutes. This navigation system accurately re-established mechanical axis without increasing surgical time.

Early Dislocation Rate in Ceramic-on-Ceramic Total Hip Arthroplasty

Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty (THA) may limit THA longevity. Bearing surfaces made of modern ceramic material, with high wear resistance and low fracture risk, have the potential to extend the longevity of THA and make the procedure more suitable for young, active patients. Concerns regarding a ceramic-on-ceramic bearing surface have included potential for a higher incidence of dislocation caused by limited modular neck length and liner options. This prospective study assessed the early dislocation incidence for a ceramic-on-ceramic THA system. Out of the 336 consecutive ceramic-on-ceramic THA performed at our institution over an 8-year (1997–2005) period, 2 (0.6%) sustained dislocation during, and none after, the first postoperative year. Both dislocations were treated with closed reduction. No component fracture or revision for any reason has occurred in this series.

Thrombosis Incidence in Unilateral vs. Simultaneous Bilateral Total Knee Arthroplasty with Compression Device Prophylaxis

This study compares the incidence of venous thromboembolic event (VTE) in 55 patients (110 knees) undergoing simultaneous bilateral TKA with 287 patients (287 knees) undergoing unilateral TKA using a mobile compression device as monotherapy prophylaxis in both groups. All patients were clinically evaluated 3months after surgery with symptomatic confirmed VTE as an endpoint. Deep venous thrombosis (DVT) was documented by duplex ultrasound and pulmonary embolism (PE) was documented by spiral CT. The simultaneous bilateral TKA group had 6 VTEs (10.9%) with 2 PEs (3.6%). The unilateral TKA group had 9 VTEs (3.1%), and 0 PE. Patients undergoing simultaneous bilateral TKA yielded more than twice the rate of VTE compared with patients undergoing unilateral TKA using a mobile compression device as sole thromboprophylactic modality.

Accuracy of a hand-held surgical navigation system for tibial resection in total knee arthroplasty

BACKGROUND Accuracy of total knee arthroplasty (TKA) implant placement and overall limb are important goals of TKA technique. METHODS The accuracy and ease of use of an accelerometer-based hand-held navigation system for tibial resection during TKA was examined in 90 patients. Preoperative goals for sagittal alignment, navigation system assembly time, resection time, and tourniquet time were evaluated. Coronal and sagittal alignment was measured postoperatively. RESULTS The average coronal tibial component alignment was 0.43° valgus; 6.7% of patients had tibial coronal alignment outside of ±3° varus/valgus. The difference between the intraoperative goal and radiographically measured posterior tibial slope was 0.5°. The average time to completion of the tibial cut was 4.6 minutes. CONCLUSION The accelerometer-based hand-held navigation system was accurate for tibial coronal and sagittal alignment during TKA, with no additional surgical time compared with conventional instrumentation.

Ceramic Liner Fracture and Impingement in Total Hip Arthroplasty

BackgroundCeramic-on-ceramic bearing surfaces were developed to provide an alternate to metal-on-polyethylene to decrease wear-induced osteolysis in total hip arthroplasty patients. In an effort to decrease the risk of ceramic acetabular component fracture or damage during implantation, a raised metal rim was added.Questions/PurposesHow many fractures or impingements have occurred in our population of patients with ceramic liners with raised rims?MethodsWith IRB-approved consent, a case series was reviewed from a single center registry and 4 of 169 patients were identified who had revision hip surgery with the ceramic liner with a raised metal rim: one for ceramic liner fracture and three for metallosis, pain, and squeaking. Implant alignment and operative findings were reviewed.ResultsOne ceramic liner fracture and three cases of metallosis from impingement of the femoral neck on the posterior elevated metal rim of the acetabular liner were observed at revision. The femoral neck in each patient had a divot that corresponded to a divot in the posterosuperior liner rim. Three of the four patients had audible squeaking or clicking prior to revision. A total of 3% of patients in this series had clinically significant impingement with this implant type.ConclusionAcoustic phenomenon in a ceramic on ceramic bearing surface should be investigated with a cross-table lateral radiograph to evaluate component position. If symptomatic impingement is demonstrated, revision should be considered to avoid failure from metallosis or fracture.

The Efficacy of a Single Daily Dose of Enoxaparin for Deep Vein Thrombosis Prophylaxis Following Total Knee Arthroplasty

Deep vein thrombosis (DVT) is a major risk following total knee arthroplasty (TKA). This prospective outcomes study evaluates the efficacy of enoxaparin 40 mg once daily for 7 days after TKA, by documenting symptomatic and asymptomatic outcomes using bilateral lower extremity duplex ultrasound upon hospital discharge and on postoperative day 21 (+/-2). In 60 extremities, duplex ultrasound demonstrated a DVT prevalence of 16.7% (10) on the day of discharge and of 11.7% (7) on postoperative day 21. No new DVT or propagation of distal to proximal DVT were noted. For this small cohort, enoxaparin 40 mg daily demonstrates effective prophylaxis for DVT in TKA patients.

The Use of Reinfusion Drains after Total Knee Arthroplasty in Patients Treated with Low Molecular Weight Heparin for Thromboembolic Prophylaxis

The effect of closed-suction drainage with red-cell reinfusion on patients receiving low molecular weight heparin (LMWH) prophylaxis after total knee arthroplasty (TKA) has not been previously studied. Therefore, our goals were to determine the effect of reinfusion drains and LMWH on allogeneic transfusions and wound complications after TKA by comparing patients treated with and without drains. Overall, transfusion rates were lower in the drain group (40% vs 15%, P=.04). Patients with reinfusion drains had a significantly higher rate of allogeneic transfusion (15.8%) than those predonating autologous blood and no drain (5.4%, P=.0003). The drain group had lower rates of wound complications (P=not significant). We were unable to demonstrate the efficacy of red-cell reinfusion as a substitute for autologous donation in TKA.