Jun-Shik Kim

Range of motion of standard and high-flexion posterior stabilized total knee prostheses. A prospective, randomized study.

BACKGROUND The restoration of posterior femoral translation has been shown to be an important factor in enhancing knee flexion after total knee arthroplasty. The purpose of this study was to compare the ranges of motion associated with standard and high-flexion posterior stabilized total knee prostheses in patients managed with simultaneous bilateral total knee arthroplasty. METHODS Fifty patients (mean age, sixty-eight years) received a standard fixed-bearing knee prosthesis in one knee and a high-flexion fixed-bearing knee prosthesis in the contralateral knee. Two patients were men, and forty-eight were women. At a mean of 2.1 years postoperatively, the patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and The Hospital for Special Surgery. RESULTS The mean postoperative Hospital for Special Surgery knee score was 90 points for the knees treated with the standard fixed-bearing prosthesis and 89.4 points for those treated with the high-flexion prosthesis. At the time of the final follow-up, the knees with the standard prosthesis had a mean range of motion of 135.8 degrees (range, 105 degrees to 150 degrees ) and those with a high-flexion prosthesis had a mean range of motion of 138.6 degrees (range, 105 degrees to 150 degrees ) (p = 0.41). No knee had aseptic loosening, revision, or osteolysis. CONCLUSIONS After a minimum duration of follow-up of two years, we found no significant differences between the groups with regard to range of motion or clinical and radiographic parameters, except for posterior femoral condylar offset.

Primary total hip arthroplasty with a second-generation cementless total hip prosthesis in patients younger than fifty years of age.

Background: The early experience with cementless total hip replacement led to design modifications to increase the initial press-fit and stability of the femoral component, to reduce the diameter of the femoral head, and to improve the acetabular component, including the locking mechanism of the shell and the quality of the polyethylene liner. We performed a prospective study to assess the results in young patients who had been followed for a minimum of eight years after treatment with a primary total hip arthroplasty with a second-generation cementless prosthesis.Methods: Eighty patients (118 hips) were included in the study. There were fifty-eight men and twenty-two women; the mean age at the time of the operation was 46.8 years (range, twenty-one to forty-nine years). We used a cementless Duraloc series-100 or 1200 acetabular component with or without screw fixation, a polyethylene liner with a 22-mm inner diameter, and a cementless Profile femoral component in all hips. The average duration of follow-up was 9.8 years (range, eight to eleven years). Clinical follow-up (with use of the Harris hip score) and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. Linear and volumetric wear were measured, and bone-remodeling and osteolysis were assessed.Results: The average Harris hip score improved from 48.8 points preoperatively to 92 points at the final follow-up examination. The prevalence of transitory thigh pain was 10% (twelve of 118 hips). There was no aseptic loosening. One hip was revised because of recurrent dislocation. The average amount of linear wear was 1.18 mm, and the average wear rate was 0.12 mm/yr. Fourteen hips (12%) had osteolysis in the calcar femorale and eleven hips (9%) had acetabular osteolysis, but all of the osteolytic lesions were <1 cm 2.Conclusions: The mechanical fixation of the anatomic fit cementless Profile stem was excellent in this study of young patients who were particularly difficult to treat because of a high prevalence of osteonecrosis and developmental dysplasia. Although there was no aseptic loosening of the components and a relatively low prevalence of osteolysis, there was a high rate of linear wear of the polyethylene liner.Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.

Alignment and orientation of the components in total knee replacement with and without navigation support: A PROSPECTIVE, RANDOMISED STUDY

Bilateral sequential total knee replacement was carried out under one anaesthetic in 100 patients. One knee was replaced using a CT-free computer-assisted navigation system and the other conventionally without navigation. The two methods were compared for accuracy of orientation and alignment of the components. There were 85 women and 15 men with a mean age of 67.6 years (54 to 83). Radiological and CT imaging was carried out to determine the alignment of the components. The mean follow-up was 2.3 years (2 to 3). The operating and tourniquet times were significantly longer in the navigation group (p < 0.001). There were no significant pre- or post-operative differences between the knee scores of the two groups (p = 0.288 and p = 0.429, respectively). The results of imaging and the number of outliers for all radiological parameters were not statistically different (p = 0.109 to p = 0.920). In this series computer-assisted navigated total knee replacement did not result in more accurate orientation and alignment of the components than that achieved by conventional total knee replacement.

Comparison of Porous-Coated Titanium Femoral Stems with and without Hydroxyapatite Coating

BACKGROUND The purpose of this prospective, randomized study was to evaluate the clinical and radiographic results associated with proximally porous-coated titanium stems that were identical in geometry but differed with regard to proximal surface treatment (with or without hydroxyapatite coating). METHODS A prospective, randomized study was performed to evaluate fifty patients (100 hips) who had undergone sequential bilateral primary total hip replacement. A proximally porous-coated titanium stem with hydroxyapatite coating was implanted on one side and a proximally porous-coated titanium stem without hydroxyapatite coating was implanted on the other side during the same operative setting in all fifty patients. A cementless acetabular component made of titanium was used in all hips. There were thirty-six men and fourteen women; the mean age at the time of the operation was 45.3 years. The mean duration of follow-up was 6.6 years. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. RESULTS The Harris hip scores in the hydroxyapatite-coated group (mean, 94 points) and non-hydroxyapatite-coated group (mean, 92 points) were similar at the final follow-up examination. The prevalence of transient pain in the thigh was 4% in each group. No acetabular or femoral component demonstrated aseptic loosening. Bone-remodeling patterns, including calcar atrophy, were similar in the two groups. No acetabular or femoral osteolysis was seen. CONCLUSIONS At a mean of 6.6 years postoperatively, the clinical and radiographic results associated with proximally porous-coated femoral prostheses with identical geometries that differed only with regard to the presence or absence of hydroxyapatite coating were similar.

Comparison of fixed-bearing and mobile-bearing total knee arthroplasties.

The purpose of the current study was to directly compare the results of fixed-bearing and mobile-bearing total knee arthroplasties in the same patient who had bilateral simultaneous total knee replacements. A fixed-bearing total knee prosthesis (AMK) was implanted in one knee and a mobile-bearing total knee prosthesis (LCS) was implanted in the other knee in 116 patients. The average age of the patients was 65 years (range, 33–70 years). The average followup was 7.4 years (range, 6–8 years). Clinical and radiographic followup was done using Knee Society and Hospital for Special Surgery knee rating systems at 6 weeks, 3 months, 6 months, 1 year after surgery, and yearly thereafter. Total knee score, pain score, mean functional score, and range of motion were comparable in both groups. Two knee replacements (2%) in one patient with AMK prostheses were revised because of complete wear of tibial bearing polyethylene. One knee replacement (1%) in one patient with an LCS prosthesis was revised because of dislocation of the medial tibial bearing polyethylene and one knee replacement (1%) in one patient with an LCS prosthesis was revised because of complete wear of the medial tibial bearing polyethylene. No knee had aseptic loosening or osteolysis in either group. After a minimum followup of 6 years, the results of fixed-and mobile-bearing total knee prostheses in the current series are favorable. However, there is no evidence to prove the superiority of the mobile-bearing total knee design.

Incidence and natural history of deep-vein thrombosis after total knee arthroplasty: A PROSPECTIVE, RANDOMISED STUDY

We have evaluated prospectively the incidence and location of deep-vein thrombosis (DVT), the risk factors for pulmonary embolism, and the natural history of thrombosis after total knee replacement (TKR) in patients who did not receive prophylactic or therapeutic treatment for DVT. We studied 227 patients who underwent primary TKR; 116 had one-stage bilateral and 111 unilateral procedures. Coagulation assays, the full blood count and blood typing tests for the serum chemical profile were undertaken in all patients on three separate occasions. Bilateral simultaneous or unilateral venograms were carried out at six or seven days after operation. Perfusion lung scanning was undertaken before and at seven or eight days after operation. Bilateral simultaneous or unilateral venograms were repeated six months after operation in all patients who had thrombi. In the 116 patients with a bilateral replacement, 97 of 232 venograms (41.8%) were positive for fresh thrombi while there were 46 positive venograms (41.4%) in the 111 patients with a unilateral replacement (p = 1.000). Of the 116 venograms in knees with a cemented replacement, 45 (38.8%) were positive for thrombi while 52 of the 116 venograms (44.8%) were positive in those with a cementless replacement (p = 0.675). Further venograms at six months after operation in all 143 limbs which had thrombi showed that all had completely resolved regardless of the size or location. No pulmonary embolism occurred as shown by negative perfusion lung scans and the absence of symptoms. Although the current prevailing opinion is that patients with thrombosis in the proximal veins should receive anticoagulant treatment, our study has shown that all thrombi regardless of their size or location resolved without causing pulmonary embolism.

Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty.

BACKGROUND Whether total knee arthroplasty with use of computer-assisted surgical navigation can improve the limb and component alignment is a matter of debate. We hypothesized that total knee arthroplasty with use of computer-assisted surgical navigation is superior to conventional total knee arthroplasty with regard to the precision of implant positioning. METHODS Sequential simultaneous bilateral total knee arthroplasties were carried out in 160 patients (320 knees). One knee was replaced with use of a computer-assisted surgical navigation system, and the other was replaced conventionally without use of computer-assisted surgical navigation. The two methods were compared for accuracy of orientation and alignment of the components as determined by radiographs and computed tomography scans. The mean duration of follow-up was 3.4 years. RESULTS The mean preoperative Knee Society score was 26 points, with an improvement to 92 points postoperatively, in the computer-assisted total knee arthroplasty group and 25 points, with an improvement to 93 points postoperatively, in the conventional total knee arthroplasty group. Preoperative and postoperative ranges of motion of the knees were similar in both groups. The operating and tourniquet times were significantly longer in the computer-assisted total knee arthroplasty group than in the conventional total knee arthroplasty group (p < 0.001). The groups were not significantly different with regard to the accuracy of component positioning and the number of outliers for the various radiographic parameters (p > 0.05). CONCLUSIONS Our data demonstrate that total knee arthroplasty with use of computer-assisted surgical navigation did not result in more accurate implant positioning than that achieved in conventional total knee arthroplasty, as determined by both radiographs and computed tomography scans.

Total knee arthroplasty in neuropathic arthropathy

We describe the results of total knee arthroplasty (TKA) undertaken for severe, neurosyphilitic Charcot arthropathy in ten patients (19 knees). A cemented condylar, constrained prosthesis was implanted in all but two knees. The mean follow-up was 5.2 years (5 to 6). The mean knee score before operation was 36.5 points (30 to 42) which improved to 76 points (58 to 90) after operation as judged by the Hospital for Special Surgery score. At final follow-up three knees (16%) had aseptic loosening which required salvage by an arthrodesis, six (31%) were functioning poorly and ten (53%) were satisfactory. We conclude that although Charcot arthropathy is not an absolute contraindication to total knee replacement, there is a high incidence of serious complications.

The long-term results of simultaneous fixed-bearing and mobile-bearing total knee replacements performed in the same patient.

We compared the results of 146 patients who received an anatomic modular knee fixed-bearing total knee replacement (TKR) in one knee and a low contact stress rotating platform mobile-bearing TKR in the other. There were 138 women and eight men with a mean age of 69.8 years (42 to 80). The mean follow-up was 13.2 years (11.0 to 14.5). The patients were assessed clinically and radiologically using the rating systems of the Hospital for Special Surgery and the Knee Society at three months, six months, one year, and annually thereafter. The assessment scores of both rating systems pre-operatively and at the final review did not show any statistically significant differences between the two designs of implant. In the anatomic modular knee group, one knee was revised because of aseptic loosening of the tibial component and one because of infection. In addition, three knees were revised because of wear of the polyethylene tibial bearing. In the low contact stress group, two knees were revised because of instability requiring exchange of the polyethylene insert and one because of infection. The radiological analysis found no statistical difference in the incidence of radiolucent lines at the final review (Students t-test, p = 0.08), most of which occurred at tibial zone 1. The Kaplan-Meier survivorship for aseptic loosening of the anatomic modular knee and the low contact stress implants at 14.5 years was 99% and 100%, respectively, with a 95% confidence interval of 94% to 100% for both designs. We found no evidence of the superiority of one design over the other at long-term follow-up.

Total hip replacement with a cementless acetabular component and a cemented femoral component in patients younger than fifty years of age

Background: We have been using hybrid total hip arthroplasty (a cementless acetabular component and a cemented stem) in young patients. The purpose of this study was to determine the prevalence of aseptic loosening, polyethylene wear, and osteolysis after the use of this technique. Methods: We studied a prospective consecutive series of sixty-four primary hybrid total hip replacements in fifty-five patients younger than fifty years old. There were forty-three men and twelve women; the average age at the time of the index operation was 43.4 years. The average duration of follow-up was 9.4 years. We used a cementless acetabular component without screw-holes and a cemented femoral component with a 22-mm head in all hips. Clinical follow-up with use of Harris hip ratings and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. The sequential annual linear and volumetric wear rates were measured, and bone-remodeling and osteolysis were assessed. Results: The mean preoperative Harris hip score was 44 points, which increased to 95 points at the time of final follow-up. No hip had aseptic loosening. One hip (2%) was revised because of late infection. The average linear wear (and standard deviation) was 0.96 ± 0.066 mm, with an average annual rate of 0.096 ± 0.013 mm. The average volumetric wear was 364.7 ± 25.2 mm3, with an average annual rate of 43.4 ± 3.5 mm3. Six hips (9%) had an osteolytic lesion of <1 cm in diameter in the calcar femorale (zone 7). Conclusions: Our results show that a hybrid arthroplasty with a cementless acetabular component and a smooth cemented femoral component (Ra, 0.6 mm) is effective for primary total hip replacement in young patients. Although there was no aseptic loosening and a low prevalence of osteolysis at the latest follow-up evaluation, the high rates of linear and volumetric wear of the polyethylene liner in these young patients remain a concern.