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Abstract High tibial osteotomy (HTO) is an established treatment option for isolated medial osteoarthritis in young and active patients. One important factor for success of this procedure is the degree of correction of the weight-bearing line. Computer-assisted navigation systems are believed to improve the precision of axis correction through intraoperative real-time monitoring. This study investigates the precision of correction of the weight-bearing line in open-wedge HTO with and without a navigation system. Nineteen legs of well-preserved human cadaver were randomly assigned to navigated (n = 10) or conventional (n = 9) HTO. In order to achieve a sufficient amount of correction in all legs the weight-bearing line was aimed at 80 percent of the width of the tibial plateau. The mean deviation of the weight-bearing line from the desired 80 percent was 1 percent in the navigated and 8.6 percent in the conventional operated legs (p = 0.002). The weight-bearing line of all navigated but only 5 of the 9 conventional operated legs was within a ± 5 percent tolerance level (p = 0.33). Navigated open-wedge HTO achieved better correction of the weight-bearing line than the conventional method in human cadaver legs. Future studies have to prove this advantage in a clinical setting and it's effect on patient outcome.

Abstract Objective High tibial osteotomy (HTO) is one treatment option for young and active patients with unicompartmental osteoarthritis. The success of this procedure substantially depends on the degree of correction of the mechanical axis. Computer-assisted navigation systems are believed to improve the precision of axis correction through intraoperative real-time monitoring. This study investigates the accuracy of limb alignment measurements with a navigation system on a cadaver specimen. Materials and methods The measurements were performed on a well-preserved cadaver specimen with a mechanical leg axis of 4° varus. Data was collected during the HTO workflow. Repeated serial measurements were undertaken by four different surgeons. After these measurements, different landmarks were deliberately set at the wrong place to examine the influence of mistakes during registration. Results There was a high intra-and interobserver reliability with a mean mechanical leg axis of 3.9° ± 0.7° and a mean error of 0.6°. The grossly incorrect placement of landmarks for knee and ankle center resulted in an incorrect mechanical leg axis of 1° valgus up to 10° varus. Conclusion The computer-assisted navigation system provided precise information about the mechanical leg axis, irrespective of the observer's experience.

Abstract Purpose Total knee arthroplasty (TKA) is an effective, but also cost-intensive health care procedure for the elderly. Furthermore, bearing demographic changes in Western Europe in mind, TKA-associated financial investment for health care insurers will increase notably and thereby catalyze discussions on ressource allocation to Orthopedic surgery. To derive a quantitative rationale for such discussions within Western Europe's health care systems, a prospective assessment of both the benefit of TKA from a patient's perspective as well as its cost effectiveness from a health care insurer's perspective was implemented. Methods A prospective cost effectiveness trial recruited a total of 65 patients (60% females), who underwent TKA in 2006; median age of patients was 66 years (interquartile range 61 - 74 years). Before and three months after surgery patients were interviewed by means of the EuroQol-5D and the WOMAC questionnaires to assess their individual benefit due to TKA and the subsequent inpatient rehabilitation. Both questionnaires' benefit estimates were transformed into the number of gained quality adjusted life years [QALYs]. Total direct cost estimates for the overall care were based on German DRG and rehabilitation cost rates [€]. The primary clinical endpoint of the investigation was the individual number of QALYs gained by TKA based on the WOMAC interview; the primary health economic endpoint was the marginal cost effectiveness ratio (MCER) relating the costs to the associated gain in quality of life [€/QALY]. Results Total direct costs for the overall procedure were estimed 9549 € in median. The WOMAC based interview revealed an overall gain of 4.59 QALYs (interquartile range 2.39 - 6.21 QALYs), resulting in marginal costs of 1795 €/QALY (1488 - 3288 €/QALY). The corresponding EuroQol based estimates were 2.93 QALYs (1.75 - 5.59 QALYs) and 3063 €/QALY (1613 - 5291 €/QALY). Logistic regression modelling identified the patients' age as the primary determinant of cost effectiveness (Likelihood Ratio p = 0.006): patients younger than 60 years showed a median gain of 6.45 QALYs and median marginal costs of 1463 €/QALY, patients between 60 - 70 years 5.47 QALYs and 1744 €/QALY, patients older than 70 years 2.76 QALYs and 3186 €/QALY. Conclusion TKA was proven to be cost effective from a health care insurer's perspective, although its marginal costs notably increased with increasing age. Note, however, that this age-related gradient in marginal cost effectiveness is of comparable order as the changes in cost effectiveness due to variation of the underlying assessment instrument.

Abstract Purpose Both open and arthroscopic Bankart repair are established procedures in the treatment of anterior shoulder instability. While the open procedure is still considered as the "golden standard" functional outcome is supposed to be better in the arthroscopic procedure. The aim of this retrospective study was to compare the functional outcome between open and arthroscopic Bankart repair. Materials and methods In 199 patients a Bankart procedure with suture anchors was performed, either arthroscopically in presence of an detached, but not elongated capsulolabral complex (40) or open (159). After a median time of 31 months (12 to 67 months) 174 patients were contacted and agreed to follow-up, 135 after open and 39 after arthroscopic Bankart procedure. Results Re-dislocations occurred in 8% after open and 15% after arthroscopic Bankart procedure. After open surgery 4 of the 11 re-dislocations occurred after a new adequate trauma and 1 of the 6 re-dislocations after arthroscopic surgery. Re-dislocations after arthroscopic procedure occured earlier than after open Bankart repair. An external rotation lag of 20° or more was observed more often (16%) after open than after arthroscopic surgery (3%). The Rowe score demonstrated "good" or "excellent" functional results in 87% after open and in 80% patients after arthroscopic treatment. Conclusion In this retrospective investigation the open Bankart procedure demonstrated good functional results. The arthroscopic treatment without capsular shift resulted in a better range of motion, but showed a tendency towards more frequently and earlier recurrence of instability. Sensitive patient selection for arthroscopic Bankart repair is recommended especially in patients with more than five dislocations.