Twelve-Year Follow-Up of Navigated Computer-Assisted Versus Conventional Total Knee Arthroplasty: A Prospective Randomized Comparative Trial.

BACKGROUND: Navigated computer-assisted total knee arthroplasty (TKA) was introduced to expedite long-term survival based on improved postoperative implantation accuracy. However, long-term outcome data after 10 years or more are rare, even available meta-analyses show controversial study results. METHODS: In a prospective randomized trial, 100 conventional TKAs (group CONV) were compared with 100 computer-assisted TKAs (group NAV) after a mean follow-up of 12 years postoperatively. A long-leg weight-bearing X-ray was performed for measuring mechanical axis of the limb, lateral distal femoral angle, and medial proximal tibial angle. Tibial slope, patella alpha angle, and radiolucent lines were also observed. Clinical investigation included evaluation of 4 different scores: Insall Knee Score, Western Ontario and MacMaster University Index score, Hospital for Special Surgery Knee Score, and visual analog scale. RESULTS: Based on a follow-up rate of at least 75%, no difference in TKA survival was found 12 years postoperatively: 91.5% in group CONV vs 98.2% in group NAV (P = .181). Since 5-year follow-up, no additional TKA revision had been performed in both groups. Group CONV showed a nonsignificant higher inaccuracy of neutral lower limb axis (1.8° ± 1.4°) compared to group NAV (1.6° ± 1.7°, P = .700). All X-ray assessments were not significant different within both study groups (P ≥ .068). Clinical examination showed no differences in evaluations (P ≥ .204). All collected outcome score results were similar (P ≥ .222). CONCLUSION: Twelve years postoperatively, no differences were found in terms of long-term survival, implantation accuracy, clinical outcome or score results.

Revision of Articular Surface Replacement (ASR) Total Hip Arthroplasty: Correlation of Perioperative Data and Early Post-Revision Outcome Results.

The articular surface replacement (ASR) total hip arthroplasty (THA) showed accelerated failure rates due to adverse-reaction to metal debris (ARMD). Literature correlating preoperative with intraoperative revision findings respectively post-revision outcome results are rare. 30 of 99 available ASR THA were revised due to ARMD. Mean post-revision follow-up term was 2.3 years. In part, preoperative data did not correlate with intraoperative revision findings. ARMD was even found in asymptomatic patients with non-elevated ion levels. Postoperative pain and metal ions decreased significantly (P ≤ 0.016). Cobalt decreased faster than chrome. Patients with intraoperative pseudotumors, osteolysis or bilateral THA did not have higher pre- or postoperative ion values (P ≥ 0.053). Females showed higher postoperative chrome levels (P=0.031). One major post-revision complication (femoral nerve palsy) and one re-revision (late onset infection) occurred.

Implication of femoral stem on performance of articular surface replacement (ASR) XL total hip arthroplasty.

Taper junctions of large diameter metal-on-metal femoral heads and femoral stems were described as metal ion generator due to accelerated wear and corrosion. However, literature about the Articular Surface Replacement (ASR) total hip arthroplasty (THA) invariably deals with stems manufactured by DePuy Orthopedics (Warsaw, IN, USA). Nothing is known whether different stems with common 12/14 mm tapers affect failure rate or ion release. 99 ASR THA (88 patients) implanted with CoxaFit or ARGE Geradschaft stems (K-Implant, Hannover, Germany) were retrospectively analyzed. After a mean follow-up of 3.5 years revision rate was 24.5%, mostly due to adverse reaction to metal debris (ARMD). CT scan revealed component loosening in 10.3% and pseudotumoral lesions in 12.6%. Elevated ion concentrations (>7 µg/l) were found in 38.6%.

Conventional versus computer-assisted technique for total knee arthroplasty: a minimum of 5-year follow-up of 200 patients in a prospective randomized comparative trial.

In the literature, studies of computer-assisted total knee arthroplasty (TKA) after mid-term period are not conclusive and long-term data are rare. In a prospective, randomized, comparative study 100 conventional TKAs (group REG) were compared with 100 computer-assisted TKAs (group NAV). Minimum follow-up was 5years. No difference in implant failure was found with 1.1% in group NAV versus 4.6% in group REG (P=0.368). Group NAV showed a significantly less mean deviation of mechanical limb axis (P=0.015), more TKAs (90% versus 81% in group REG) were within 3° varus/valgus and a higher tibial slope and lateral distal femoral angle (LDFA) accuracy was found (P≤0.034). Clinical investigational parameters showed no differences (P≥0.058). Insall and HSS score total were also higher in group NAV (P≤0.016).

Comparison of two minimally invasive implantation instrument-sets for total knee arthroplasty.

Several choices of instrument systems are available for minimally invasive surgical approaches. There are reports that one alternative, the quadriceps sparing, side-cutting instrumentation, results in diminished implantation accuracy. A total of 108 patients were randomized to undergo TKA either using side-cutting implant instrumentation (Group A) or anterior-posterior mini-incision instrumentation (Group B). All TKAs were operated on with a minimal invasive, mini-midvastus surgical approach. 50% of the TKAs were performed with computer-assistance in each cohort. The radiographic parameters, clinical outcomes and knee scores were evaluated preoperatively and 3 months postoperative. In Group B, we found significantly higher accuracy for the mechanical axis of the limb (range +/-3 degrees: Group A 54% versus Group B 89%, p = <0.001), medial proximal tibial angle (range +/-3 degrees: Group A 85% versus Group B 98%, p = <0.027) and tibial slope (range +/-3 degrees: Group A 59% versus Group B 85%, p = <0.007). The application of the navigation system could only significantly reduce outliers (accuracy >3 degrees) in Group B. Clinical outcomes and knee scores were similar in both groups and were not influenced by computer-assistance. Using the anterior-posterior, mini-incision instruments for minimally invasive TKA will lead to higher implantation accuracy when compared to the quadriceps sparing side-cutting instrumentation. The navigation technique could not compensate for shortcomings of the side-cutting instrumentation. The clinical relevance of this study is that the quadriceps sparing side-cutting instrumentation should not be used for TKA because of unacceptable reduced implantation accuracy.

Accuracy of side-cutting implantation instruments for total knee arthroplasty.

A new generation of implantation instruments were developed for quadriceps sparing surgical approaches during total knee arthroplasty (TKA). There is little information on the accuracy of the bone cuts performed with the side-cutting technique. A total of 100 patients were randomized to undergo computer-assisted TKA or non-navigated TKA using a mini-subvastus surgical approach and side-cutting implant instrumentation. The radiographic parameters, clinical outcomes and knee scores were evaluated 3 months postoperative. The mechanical axis of the limb was within 3 degrees varus/valgus in 76% of the patients who had navigated procedures versus 66% of patients who had conventional surgery. The tibial slope showed a rate of inaccuracy of 3 degrees or less for 78% of the patients in the navigated total knee arthroplasty group versus 66% of the patients in the conventional group. Clinical outcomes and knee scores were similar in both groups. The navigation technique could not compensate for shortcomings of the implantation instruments.

Imageless navigation for TKA increases implantation accuracy.

Because we are performing TKAs on heavier, younger patients, greater stress is being put on the implants and is increasing the importance of implantation accuracy. We performed a prospective randomized study to compare the radiographic results and the 3-month clinical outcomes in 100 patients who had TKAs using an imageless navigation system with 100 patients treated using conventional implantation instruments. We measured component alignment by standard radiographs. Clinical outcomes were based on the Insall score, anterior knee pain, feeling of instability, and the step test. The mechanical axis of the limb was within 3 degrees varus/valgus in 92% of the patients who had navigated procedures versus 76% of patients who had conventional surgery. The tibial slope showed a rate of inaccuracy of 3 degrees or less for 98% of the patients in the navigated TKA group versus 80% of the patients in the conventional group. The surgical time was longer for navigated TKA than for the conventional procedure (88 +/- 16 versus 68 +/- 18 minutes, respectively). Clinical outcomes and postoperative blood loss were similar in both groups. The navigation system increased implantation accuracy but did not prevent outliers and did not solve the problems associated with identifying and obtaining accurate component rotation.

Frameless stereotactic cannulation of the foramen ovale for ablative treatment of trigeminal neuralgia.

OBJECTIVE: Ablative neurosurgical treatment of trigeminal neuralgia, including percutaneous radiofrequency thermocoagulation, requires cannulation of the foramen ovale. To maximize patient security and cannulation success, a frameless stereotactic system was evaluated in a phantom study, a cadaveric study, and a preliminary clinical trial. METHODS: Frameless stereotaxy using an optical navigation system, an aiming device, and a noninvasive vacuum mouthpiece-based registration and patient fixation technique was used for the targeting of a test body based on 1-, 3-, and 5-mm axial computed tomographic slices and of the foramen ovale in three cadavers and 15 patients based on 3-mm axial computed tomographic slices. RESULTS: The mean normal (x/y) localization accuracy/standard deviation (n = 360) was 1.31/0.67 mm (1-mm slices), 1.38/0.65 mm (3-mm slices), and 1.84/0.96 mm (5-mm slices). Significantly better results were achieved with 1- and 3-mm slices when compared with 5-mm slices (P < 0.001). The foramen ovale (3 x 6 mm) was successfully cannulated at the first attempt in all cadavers and patients, which indicates clinical localization accuracies better than 1.5 mm in the anteroposterior and 3 mm in the medial-lateral directions. CONCLUSION: Based on the noninvasive Vogele-Bale-Hohner vacuum mouthpiece, there is no need for invasive head clamp fixation. Imaging, real laboratory simulation, and the actual surgical intervention can be separated in time and location. The presented data suggest that frameless stereotaxy is a predictable and reproducible procedure, which may enhance patient security and cannulation success independent of the surgeon's experience.

Two-year outcomes of computed tomography-based and computed tomography free navigation for total knee arthroplasties.

UNLABELLED: Optimal component position in all planes and well-balanced soft tissues facilitate a good clinical outcome and long-term survival after total knee arthroplasties. We investigated the accuracy of implantation of navigated total knee arthroplasties at 3 months followup and the influence on the clinical outcome at 2 years followup. Forty-four patients (44 procedures) were enrolled in our prospective study. One half of the surgeries were performed using a computed tomography-based navigation system, and half were performed with imageless navigation. Outcomes were based on the Insall knee score parameters, anterior knee pain, patient satisfaction, feeling of instability, and step test. The radiographic parameters were the mechanical axis, tibial slope, lateral distal femoral angle, and medial proximal tibial angle. The radiographic measurements were similar in both groups (patients within +/- 3 degrees inaccuracy range in computed tomography-based/imageless groups; mechanical axis 86%/81%, tibial slope 95%/91%, lateral distal femoral angle 95%/91%, medial proximal tibial angle 91%/95%). The imageless system provided equal radiographic results, but we found improved ligament balancing in the computed tomography free group. The computed tomography-based approach has a good pre-operative planning procedure, but is more expensive and time consuming. LEVEL OF EVIDENCE: Therapeutic Study, Level II. See the Guidelines for Authors for a complete description of levels of evidence.