Navigated cementless total knee arthroplasty - medium-term clinical and radiological results.

PURPOSE: The objective of this prospective study was to evaluate the medium-term clinical and radiological results after navigated cementless implantation, without patella resurfacing, of a total knee endoprosthesis with tibial and femoral press-fit components, with a focus on survival rate and clinical outcome. The innovation is the non-cemented fixation together with the use of a navigation system. SCOPE AND METHODS: Sixty patients with gonarthrosis were included consecutively in this study. In all cases, the cementless Columbus total knee endoprosthesis with a coating out of pure titanium was implanted, using a navigation system. The Knee Society Score showed a statistically significant increase from 75 (± 21.26) before surgery to 180 (± 16.15) after a mean follow-up of 5.6 (± 0.25) years. The last radiological examination revealed no osteolysis. No radiolucent lines were seen at any time in the area of the femoral prosthetic components. In the tibial area, radiolucent lines were seen in 24.4 % of the cases, mostly in the distal uncoated part of the stem. During follow-up, no prosthesis had to be replaced because of aseptic loosening while in 2 cases revision surgery was necessary due to septic loosening and in 1 case due to unexplainable pain. RESULTS AND CONCLUSIONS: Navigated cementless implantation of the Columbus total knee endoprosthesis yielded good clinical and radiological results in the medium term. The excellent radiological osteointegration of the prosthetic components, coated with a microporous pure titanium layer and implanted with a press-fit technique, should be emphasized.

Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosity-trochlear groove distance.

PURPOSE: The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. METHODS: Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity-trochlear groove (TT-TG) distance. RESULTS: Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. CONCLUSIONS: The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. LEVEL OF EVIDENCE: Level IV, diagnostic case-control study.

Impact of monopolar radiofrequency energy on subchondral bone viability.

The purpose of this study was to analyze the impact of monopolar radiofrequency energy treatment on subchondral bone viability. The femoral grooves of six chinchilla bastard rabbits were exposed bilaterally to monopolar radiofrequency energy for 2, 4 and 8 s, creating a total of 36 defects. An intravital fluorescence bone-labeling technique characterized the process of subchondral bone mineralization within the 3 months following exposure to radiofrequency energy and was analyzed by widefield epifluorescence optical sectioning microscopy using an ApoTome. After 2 s of radiofrequency energy exposure, regular fluorescence staining of the subchondral bone was evident in all samples when compared to untreated areas. The depth of osteonecrosis after 4 and 8 s of radiofrequency energy treatment averaged 126 and 942 microm at 22 days (P < .05; P < .01). The 4 s treatment group showed no osteonecrosis after 44 days whereas the depth of osteonecrosis extended from 519 microm at 44 days (P < .01), to 281 microm at 66 days (P < .01) and to 133 microm at 88 days (P < .05) after 8 s of radiofrequency energy application. Though radiofrequency energy may induce transient osteonecrosis in the superficial zone of the subchondral bone, the results of this study suggest that post-arthroscopic osteonecrosis appears to be of only modest risk given the current clinical application in humans.

Five- to 10-year results using a noncemented modular revision stem without bone grafting.

The aim of the study was to evaluate the 5- to 10-year results (mean, 6.2 years) of a modular uncemented revision stem (Profemur-R). From a total series of 184 consecutive stem revisions, the first 73 were evaluated. The implant was fixed without bone grafting in all cases. The average Harris hip score increased from 40 to 75. A complete remodeling of bone defects could be documented radiographically in 70% of the cases and a partial restoration in 30%. Progressive subsidence appeared in 2 stems. Three rerevisions were required, including 1 septic case. The survival rate with aseptic loosening as the end point was 96% over an average of 10 years. The revision prosthesis examined in this study can be considered a viable and useful option to reconstruct femoral defects in revision hip arthroplasty.

Comparison of CT, MRI, and radiographs in assessing pelvic osteolysis: a cadaveric study.

In this study, we compared the accuracy of radiography, computed tomography, and magnetic resonance imaging in assessing periacetabular osteolytic lesions. Using a previously published cadaver model, we created 87 lesions in pelves implanted with total hip replacement components. The sensitivity for detecting lesions was 51.7% for radiography, 74.7% for computed tomography, and 95.4% for magnetic resonance imaging. For all three techniques, sensitivity increased as lesion size increased. Magnetic resonance imaging emerged as the most effective tool for detecting small periacetabular osteolytic lesions (< or = 3 cm). For lesions larger than 3 cm, which are of more concern clinically, computed tomography and magnetic resonance imaging were effective in identifying lesions with detection rates greater than 80%. For radiography and computed tomography, lesion detection was dependent on lesion location, whereas magnetic resonance imaging had consistently good sensitivity in all lesion locations. Although the mean volumetric errors for computed tomography and magnetic resonance imaging (0.3 cm and 0.8 cm) were small compared with mean lesion volume (6.1 cm), computed tomography was more accurate than magnetic resonance imaging at measuring lesion volume, with a lower mean absolute error. This study verifies the problems associated with radiographic detection of osteolysis while showing the effectiveness of computed tomography and magnetic resonance imaging in determining the presence of lesions and assessing their three-dimensional volume.

Magnetic resonance imaging in the evaluation of periprosthetic acetabular osteolysis: a cadaveric study.

Periprosthetic osteolysis is a well recognized complication of total hip arthroplasty that leads to implant failure. The ability to accurately assess and visualize the position and volume of periacetabular bone defects is paramount for clinical observation and medical treatment, as well as pre-operative planning of revision surgery. We have developed a modified magnetic resonance imaging (MRI) protocol that is useful in detection and quantification of periacetabular bone loss. The purpose of this study is to compare MRI to plain film analysis in the assessment of periacetabular bone loss using a cadaver model. MRI was 95% sensitive in the detection of lesions. Specificity was 98%, and accuracy was 96%. Lesion detection was not statistically dependent on lesion location (p=0.27). The mean absolute error in determining lesion size was 0.8+/-2.2 cm3. There was a correlation between increasing lesion size and lesion detection (p=0.02, logistic regression). The largest lesion that was missed by MRI analysis measured 2.8 cm3, and all lesions 3.0 cm3 were correctly identified, with a relative error volume measurement of 12.4+/-25.3%. This correlated to an absolute error of 1.4+/-2.4 cm3. Using conventional radiographic analysis, the overall sensitivity of lesion detection was 52%, and the specificity was 96%. Using plain film analysis, identification of true lesions depended on the location with 83% of ilial lesions, 64% of pubic lesions, 55% of ischial lesions, and 0% of posterior wall lesions correctly identified. The modified MRI technique utilized did allow for accurate visualization of simulated osteolytic lesions, and may provide a suitable noninvasive method to provide serial assessment of clinical periacetabular osteolysis without the use of ionizing radiation.

Sensitivity and specificity of plain radiographs for detection of medial-wall perforation secondary to osteolysis.

Medial-wall perforation secondary to pelvic osteolysis impacts planning of acetabular revision surgery and may result in pelvic fracture. We compared commonly used radiographic signs for detecting medial-wall perforation (ballooning or discontinuity of Kohler's line or the iliopubic line) to findings from computed tomography (CT) in 27 cementless total hip arthroplasty patients with pelvic osteolysis. Used alone, none of the radiographic signs examined were reliable for detecting medial-wall perforation. When assessed together, however, the development of a discontinuity of Kohler's line, the iliopubic line, or both on anteroposterior pelvic radiographs was a reliable indicator for the presence of medial-wall perforation. Thus, the authors recommend a CT scan to evaluate the integrity of the medial wall when a discontinuity of Kohler's line or the iliopubic line has occurred and a revision surgery is planned.

Advancement and separation of apex hole eliminators with cementless Duraloc 100 cups. A report of nineteen cases.

BACKGROUND: From 1992 to 1996, we performed 541 cementless total hip arthroplasties using a Duraloc 100 acetabular component with an apex hole eliminator that did not have a positive stop design. During routine follow-up radiographic evaluation, we noted several hips with advanced or separated hole eliminators. This study presents the clinical consequences of this occurrence and its relationship to polyethylene wear and osteolysis. METHODS: A total of 541 hips (358 with a minimum duration of follow-up of five years) were evaluated clinically with use of the method of Merle D'Aubigné and Postel. Anteroposterior pelvic and iliac oblique radiographs were used to evaluate polyethylene wear, osteolysis, hole eliminator position, and component stability. RESULTS: Nineteen hips that had been followed for an average of eighty-nine months showed advancement or complete separation of the hole eliminator on radiographic evaluation. In most hips, advancement of the hole eliminator was visible on only the iliac oblique radiograph. In all but one hip with separation of the hole eliminator, complete plug separation was detectable on both the iliac oblique and anteroposterior pelvic radiographs. No association was found between polyethylene wear and either advancement or separation of the hole eliminator. No osteolysis was visible radiographically in the hips with hole eliminator advancement, but osteolysis was always visible in the hips that had complete separation of the hole eliminator. CONCLUSIONS: The hole eliminator has been redesigned since November 1995 to prevent possible advancement. However, patients with earlier designs should be followed carefully because advancement or separation can be expected in about 5% of the patients who have been followed for a minimum of five years. Despite this complication, which is seen radiographically, all patients were satisfied with the function of the hip. We do not recommend surgery solely to remove or replace the hole eliminator.

Management of patients with acetabular socket wear and pelvic osteolysis.

Polyethylene wear and pelvic osteolysis are the most common late complications associated with stable cementless total hip implants. This manuscript describes the diagnostic strategies and treatment algorithm used at the senior author's (C.A.E) institution for patients with wear and pelvic osteolysis. This evolving management strategy is based on our experiences and ongoing research. We discuss patient selection, the evaluation of acetabular liner wear, the diagnosis of pelvic osteolysis, the timing of revision, and treatment strategies. According to this algorithm, we revise asymptomatic hips with pending or complete wear-through of the acetabular liner. We also recommend revision for most symptomatic patients with pelvic osteolysis and for patients with large pelvic osteolytic bone defects or a documented increase in osteolytic lesion size in an area of the cementless acetabular component in which a load transfer between the implant and the surrounding bone is likely to occur.