S. B. Haas

Meta-analysis of thromboembolic prophylaxis after total knee arthroplasty

We performed a meta-analysis of the English literature to assess the efficacy of four common regimes for thromboembolic prophylaxis after total knee arthroplasty: aspirin, warfarin, low-molecular-weight heparin (LMWH) and pneumatic compression. We reviewed 136 articles and abstracts published between January 1980 and December 1997. Papers not using routine venography and a lung scan or angiography to detect deep-venous thrombosis (DVT) and pulmonary emboli (PE) respectively, were excluded. Of the 136 studies, 23 with 6001 patients were selected. The incidence of DVT was 53% (1701/3214) in the aspirin group, 45% (541/1203) in the warfarin group, 29% (311/1075) in the LMWH group, and 17% (86/509) in the pneumatic compression device group. Intermittent pneumatic compression devices and LMWH were significantly better than warfarin (p < 0.0001) or aspirin (p < 0.0001) in preventing DVT. The incidence of asymptomatic PE was 11.7% in the aspirin group (222/1901), 8.2% (101/1229) in the warfarin group and 6.3% (24/378) in the pneumatic compression group. No studies with LMWH used routine lung scans. Warfarin and pneumatic compression were significantly better than aspirin in preventing asymptomatic PE (p < 0.05). The incidence of symptomatic PE was 1.3% (23/1800) in the aspirin group, 0.4% (2/559) in the warfarin group, 0.5% (2/416) in the LMWH group and 0% (0/177) in the pneumatic compression group. No statistically significant difference was noted between the above prophylatic regimes due to the very small incidence of symptomatic PE. Prophylaxis for thromboembolic disease in TKA may have to include a combination of some of the above regimes to incorporate their advantages.

Pneumatic sequential-compression boots compared with aspirin prophylaxis of deep-vein thrombosis after total knee arthroplasty.

This prospective, randomized study was undertaken to compare the effectiveness of pneumatic sequential-compression boots with that of aspirin in preventing deep-vein thrombosis after total knee arthroplasty. Patients were randomly assigned to one of two prophylactic regimens: compression boots or aspirin. One hundred and nineteen patients completed the study. Seventy-two patients had unilateral arthroplasty and forty-seven, one-stage bilateral arthroplasty. In the unilateral group, the incidence of deep-vein thrombosis was 22 per cent for the patients who used compression boots compared with 47 per cent for those who received aspirin (p less than 0.03). In the bilateral group, the incidence of deep-vein thrombosis was 48 per cent for the patients who used compression boots compared with 68 per cent for those who received aspirin (p less than 0.20). The results confirm the effectiveness of compression boots in the treatment of patients who have had unilateral total knee arthroplasty. Despite the use of compression boots, however, patients who had bilateral arthroplasty were at greater risk for the development of deep-vein thrombosis.

Effects of epidural anesthesia on the incidence of deep-vein thrombosis after total knee arthroplasty.

Epidural anesthesia has been reported to reduce the prevalence of deep-vein thrombosis after total hip arthroplasty compared with the prevalence after general anesthesia. However, the effect of epidural anesthesia on the rate of thrombosis after total knee arthroplasty has not been reported previously, to our knowledge. A review was conducted of 705 total knee arthroplasties (541 patients) that had been performed by a single surgeon between September 1984 and December 1988. During this period, the operative technique, the protocol for rehabilitation, and the regimen for prophylaxis against thromboembolism did not change meaningfully. The patients received either epidural or general anesthesia. Preoperative and postoperative perfusion scans of the lungs and a venogram of the lower limb or limbs that had been operated on were done for all patients. For the 227 patients who had received epidural anesthesia, the over-all rate of deep-vein thrombosis was 48 per cent, which was significantly lower than the 64 per cent incidence in the 264 patients who had received general anesthesia (p less than 0.0001). The greatest reduction was in the occurrence of proximal thrombosis, which was identified in 9 per cent of the patients who had had general anesthesia but in only 4 per cent of those who had had epidural anesthesia (p less than 0.05). The use of epidural anesthesia reduced the incidence of proximal thrombosis after both unilateral and one-stage bilateral arthroplasty.

Randomized trial of epidural versus general anesthesia: outcomes after primary total knee replacement.

To compare the effects of epidural anesthesia and general anesthesia on early postoperative outcomes after unilateral primary total knee replacement, 262 patients were randomly assigned to receive either epidural or general anesthesia. All patients received a common rehabilitation protocol including a standardized assessment of progress. One hundred eighty-eight patients received a common thromboembolic prophylaxis protocol with postoperative aspirin, and had a standardized surveillance protocol to detect thromboembolic complications. Deep vein thrombosis was determined by venography on the operative limb, and pulmonary embolism was determined by comparison of preoperative and postoperative lung perfusion scans. The epidural anesthesia group reached all rehabilitative milestones earlier postoperatively than did the general anesthesia group, with a statistically significant earlier attainment of stair climbing. The incidence of deep vein thrombosis was 40% with epidural anesthesia, and 48% with general anesthesia. There were no clots proximal to the popliteal veins. The incidence of pulmonary embolism on lung scan was 12% with epidural anesthesia and 9% with general anesthesia. Epidural anesthesia is associated with more rapid achievement of postoperative in hospital rehabilitation goals after total knee replacement. A minor reduction in postoperative deep vein thrombosis rate was observed with epidural anesthesia, but this did not reach statistical significance. No difference in early postoperative pulmonary embolism was observed between the 2 types of anesthesia.

Total knee arthroplasty after open reduction and internal fixation of fractures of the tibial plateau: a minimum five-year follow-up study.

Background: There is little information in the literature regarding the outcome of total knee arthroplasty following open reduction and internal fixation of fractures of the tibial plateau. The goal of this study was to evaluate the results of such procedures after a minimum of five years of follow-up. Methods: We retrospectively analyzed the outcomes of fifteen total knee arthroplasties performed at an average of 38.6 months (range, eight months to eleven years) after open reduction and internal fixation of a fracture of the tibial plateau in fifteen consecutive patients. The average duration of follow‐up after the total knee arthroplasty procedures was 6.2 years (range, 5.4 to 11.1 years). The average age of the patients was fifty‐six years (range, thirty‐seven to sixty‐eight years) at the time of the arthroplasty. We evaluated the outcomes on the basis of the Hospital for Special Surgery knee score, the Short Form-36 score, and radiographs of the knees. Results: The average Hospital for Special Surgery knee score was 51 points (range, 20 to 74 points) before the arthroplasty, and it increased to 80 points (range, 44 to 91 points) postoperatively. Four knees were scored as excellent, eight had a good result, one was rated as fair, and two had a poor result. The average Short Form-36 scores were 58.0 points for general health, 72.4 points for bodily pain, 72.1 points for mental health, 58.3 points for physical functioning, 84.6 points for physical role functioning, 81.0 points for social functioning, and 57.7 points for vitality. The average active postoperative arc of motion was 105° (range, 70° to 135°) compared with 87° (range, 20° to 125°) preoperatively. Incomplete radiolucencies were noted on all of the postoperative radiographs made after the total knee arthroplasties. There was a high rate of infection (three patients), patellar tendon disruption (two patients), and postoperative secondary procedures (three patients required closed manipulation). The patients with infection were considered to have a failure of treatment: two required arthrodesis, and one required a two-stage exchange. Conclusion: On the basis of our results, we concluded that total knee arthroplasty after open reduction and internal fixation of a fracture of the tibial plateau decreases pain and improves knee function, but the procedure is technically demanding and is associated with a high failure rate (five of fifteen).

Disassembly of a modular femoral component during closed reduction of the dislocated femoral component. A case report.

A thirty-four-year-old man had had internal fixation ofa slipped capital femoral epiphysis of the right hip in 1970. In 1980, a Charnley-Muller ponent. After this revision, the patient had had increasing pain and eventually needed two crutches to walk. In 1989, the patient was seen by us. The grossly loose components were replaced by a Harris-Galante acetabular component (Zimmer, Warsaw, Indiana) and a cemented Bias femoral component (Zimmer) with a twenty-eight-millimeter-diameter ‘ ‘plus ten’ ‘ head assembly. The head was impacted onto the taper with two or three sharp blows of a mallet and could not be removed by manual distraction. The patient’s recovery was uneventful until four weeks postopera-

Venous haemodynamics after total knee arthroplasty

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems. The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient. The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%. All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.

CORRECTING SEVERE VALGUS DEFORMITY: TAKING OUT THE KNOCK

Valgus knee deformity can present a number of unique surgical challenges for the total knee arthroplasty (TKA) surgeon. Understanding the typical patterns of bone and soft-tissue pathology in the valgus arthritic knee is critical for appropriate surgical planning. This review aims to provide the knee arthroplasty surgeon with an understanding of surgical management strategies for the treatment of valgus knee arthritis. Lateral femoral and tibial deficiencies, contracted lateral soft tissues, attenuated medial soft tissues, and multiplanar deformities may all be present in the valgus arthritic knee. A number of classifications have been reported in order to guide surgical management, and a variety of surgical strategies have been described with satisfactory clinical results. Depending on the severity of the deformity, a variety of TKA implant designs may be appropriate for use. Regardless of an operating surgeons preferred surgical strategy, adherence to a step-wise approach to deformity correction is advised. Cite this article: Bone Joint J 2017;99-B(1 Supple A):60-4.

Oxidised zirconium versus cobalt alloy bearing surfaces in total knee arthroplasty : 3D laser scanning of retrieved polyethylene inserts

Aims We sought to establish whether an oxidised zirconium (OxZr) femoral component causes less loss of polyethylene volume than a cobalt alloy (CoCr) femoral component in total knee arthroplasty. Materials and Methods A total of 20 retrieved tibial inserts that had articulated with OxZr components were matched with 20 inserts from CoCr articulations for patient age, body mass index, length of implantation, and revision diagnosis. Changes in dimensions of the articular surfaces were compared with those of pristine inserts using laser scanning. The differences in volume between the retrieved and pristine surfaces of the two groups were calculated and compared. Results The loss of polyethylene volume was 122 mm3 (standard deviation (sd) 87) in the OxZr group and 170 mm3 (SD 96) in the CoCr group (p = 0.033). The volume loss in the OxZr group was also lower in the medial (72 mm3 (SD 67) versus 92 mm3 (SD 60); p = 0.096) and lateral (49 mm3 (SD 36) versus 79 mm3 (SD 61); p = 0.096) compartments separately, but these differences were not significant. Conclusion Our results corroborate earlier findings from in vitro testing and visual retrieval analysis which suggest that polyethylene volume loss is lower with OxZr femoral components. Since both OxZr and CoCr are hard surfaces that would be expected to create comparable amounts of polyethylene creep, the differences in volume loss may reflect differences in the in vivo wear of these inserts.