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High tibial osteotomy is an established technique for the treatment of varus malaligned knees. This study analyses the difference between the amount of correction in the preoperative planning and the postoperative result. Furthermore, it compares the difference of the accuracy between open-wedge osteotomy and closed-wedge osteotomy. About 61 patients were either treated with open-wedge or closed-wedge high tibial osteotomy. Preoperative planning and postoperative analysis were performed with a special planning software. The influence of operative technique, aetiology, age, number of previous surgeries, amount of correction and accuracy of the correction compared to the preoperative planning were analysed. The overall postoperative mechanical axis differed form preoperative planning by 2.1° ± 1.7°. The accuracy in the open-wedge group (1.7° ± 1.6°) was significantly higher than in the closed-wedge group (2.6° ± 1.8°; P  = 0.038). In patients with congenital varus deformity, the accuracy of the correction was significantly higher than in patients with post-traumatic deformity. The authors recommend open-wedge technique in combination with fixed-angle plates for high tibial osteotomy.

High tibial osteotomy (HTO) is an established therapy for the treatment of symptomatic varus malaligned knees. A main reason for disappointing clinical results after HTO is the under‐ and overcorrection of the mechanical axis due to insufficient intraoperative visualisation. Twenty legs of fresh human cadaver were randomly assigned to navigated open‐wedge HTO ( n =10) or conventional HTO using the cable method ( n =10). Regardless of the pre‐existing alignment, the aim of all operations was to align the mechanical axis to pass through 80% of the tibial plateau (beginning with 0% at the medial edge of the tibial plateau and ending with 100% at the lateral edge). This overcorrection was chosen to ensure a sufficient amount of correction. Thus, the medial proximal tibia angle (MPTA) increased by 9.1±2.9° (range 5.2°–12.3°) on the average after navigated HTO and by 8.9±2.9° (range 4.7°–12.6°) after conventional HTO. After stabilization with a fixed angle implant, the alignment was measured by CT. After navigated HTO, the mechanical axis passed the tibial plateau through 79.7% (range 75.5–85.8%). In contrast, after conventional HTO, the average intersection of the mechanical axis was at 72.1% (range 60.4–82.4%) ( P =0.020). Additionally, the variability of the mean corrections was significantly lower in the navigated group (3.3% vs. 7.2%, P =0.012). Total fluoroscopic radiation time was significantly lower in the navigated group ( P =0.038) whereas the mean dose area product was not significantly different ( P =0.231). The time of the operative procedure was 23 min shorter after conventional HTO ( P <0.001). Navigation systems provide intraoperative 3‐dimensional real time control of the frontal, sagittal, and transverse axis and may increase the accuracy of open‐wedge HTO. Future studies have to analyse the clinical effects of navigation on corrective osteotomies.

Until now, there has been no in vitro model that duplicates the environment of bone marrow. The purpose of this study was to analyze proliferation and differentiation of human bone marrow stromal cells (hBMSC) under the influence of continuous perfusion and cyclic mechanical loading. hBMSC of seven individuals were harvested, grown in vitro, and combined. 10 6 hBMSC were seeded on a bovine spongiosa disc and incubated in a bioreactor system. Cell culture was continued using three different conditions: Continuous perfusion (group A), 10% cyclic compression at 0.5 Hz (group B) and static controls (group C). After 24 h, 1, 2, and 3 weeks, we determined cell proliferation (MTS-assay) and osteogenic differentiation (osteocalcin ELISA, Runx2 mRNA). Tenascin-C mRNA was quantified to exclude fibroblastic differentiation. In groups A and B, proliferation was enhanced after 2 weeks (48.6±19.6×10 3 (A) and 44.6±14.3×10 3 cells (B)) and after 3 weeks (46.6±15.1×10 3 (A) and 44.8±10.2×10 3 cells (B)) compared with controls (26.3±10.8×10 3 (2 weeks) and 17.1±6.5×10 3 cells (3 weeks), p<0.03). Runx2 mRNA was upregulated in both stimulated groups after 1, 2, and 3 weeks compared to control (group A, 1 week: 5.2±0.7-fold; p<0.01, 2 weeks: 4.4±1.9-fold; p<0.01, 3 weeks: 3.8±1.7-fold; p=0.013; group B, 1 week: 3.6±1.1-fold, p<0.01, 2 weeks: 4.2±2.2-fold, p<0.01; 3 weeks: 5.3±2.7-fold, p<0.01). hBMSC stimulated by cyclic compression expressed the highest amount of osteocalcin at all time points (1 week: 294.5±88.4 mg/g protein, 2 weeks: 294.4±73.3 mg/g protein, 3 weeks: 293.1±83.6 mg/g protein, p⩽0.03). The main stimulus for cell proliferation in a 3-dimensional culture of hBMSC is continuous perfusion whereas mechanical stimulation fosters osteogenic commitment of hBMSC. This study thereby contributes to the understanding of physical stimuli that influence hBMSC in a 3-dimensional cell culture system.

IntroductionIn the present study, the long-term results of 11 patients with anterior sternoclavicular joint (SCJ) instability are reported. All included patients had an anterior SCJ instability and due to delayed diagnosis, operative treatment was not done immediately.MethodThe patients had a mean age of 29.2 years (range 16–63 years). One patient sustained concomitant injuries. Six patients had resection arthroplasty. Five patients had reconstruction of the SCJ with transosseous tension band PDS fixation or ligament reconstruction with additional wire cerclage. The results of treatment were evaluated after a mean follow-up period of 9.9 years (range 1–27 years) using the ASES, DASH and power-, age and gender adjusted Constant–Murley Score.ResultsIn general, the mean values of the different scores (ASES 79.8; DASH 11.8; Constant–Murley 81%) demonstrated good outcome. The outcome evaluation of the patients who had SCJ reconstruction did not differ significantly from the patients who had medial resection arthroplasty. The rate of postoperative pain or instability was low using visual analog scale and did not differ significantly between the groups. The outcome results of the reconstruction group were equal to the results of the resection group when SCJ-reconstruction was performed soon after SCJ injury. One patient in the resection group (6 patients) demonstrated poor results due to continued instability of the remaining clavicle.ConclusionWe concluded that patient selection and a specific clinical indication for operative treatment are crucial. Resection of the medial clavicle results in good functional outcome when the costoclavicular ligament is preserved or reconstructed.

PurposeSuccessful outcome after total knee arthroplasty (TKA) requires precise realignment of the mechanical axis. The intraoperative assessment of the mechanical axis is difficult. Intraoperatively, the effect of weight bearing on the lower limb mechanical axis is ignored. We developed a custom-made mechanical loading device to simulate weight-bearing conditions intraoperatively and analysed its effect on the mechanical axis during TKA.MethodsMeasurements of the mechanical axis were obtained during 30 consecutive primary TKAs in osteoarthritic patients using image-free knee navigation system. Half body weight was applied intraoperatively using our device to quantify the effect of intraoperative load application on the mechanical axis, thus receiving indirect information about soft tissue balancing. Furthermore, the intraobserver and interobserver reliability of navigated mechanical axis measurement with and without load was determined.ResultsBefore TKA, mean mechanical axis was 4.0° ± 4.9° without load. Under loading conditions, the mean change of the mechanical axis was 2.1° ± 2.8°. Repetitive measurements of the senior surgeon and junior surgeon revealed a high intraobserver (ICC 0.997) and interobserver reliability (ICC 0.998). The registration of the mechanical axis without and with application of intraoperative loading demonstrated no significant differences during insertion of the trial components (SD 0.29 ± 0.29) and after the definitive component cementation (SD 0.63 ± 0.44).ConclusionsIntraoperative quantification and analysis of the mechanical lower limb axis applying defined axial loading by our custom-made loading apparatus is reliable. Ligament stability was unbalanced before TKA and balanced after TKA. For TKA, intraoperative simulation of weight bearing may be helpful to quantify, control and correct knee stability and its influence of mechanical axis.

IntroductionRuptures of the anterior cruciate ligament are being diagnosed with increasing frequency in skeletally immature individuals. It was our aim to investigate the graft remodelling process following an autologous, transphyseal reconstruction of the anterior cruciate ligament (ACL) in skeletally immature sheep. We hypothesized that the ligamentisation process in immature sheep is quicker and more complete when compared to adult sheep.Materials and methodsSkeletally immature sheep with an age of 4 months underwent a fully transphyseal ACL reconstruction using an autologous tendon. The animals were subsequently sacrificed at 3, 6, 12 and 24 weeks following surgery. Each group was characterised histomorphometrically, by immunostaining (VEGF, SMA), by transmission electron microscopy (TEM) and biomechanically (UFS Roboter).ResultsThe histomorphometric analysis and presence of VEGF and SMA positive cells demonstrated a rapid return to a ligament like structure. The biomechanical analysis revealed an anteroposterior translation that was still increased even 6 months following surgery.ConclusionAs in adult sheep models, the remodeling of a soft tissue graft used for ACL reconstruction results in a biomechanically inferior substitute. However, the immature tissue seems to remodel faster and more complete when compared to adults.

Inaccurate coronal plane realignment is a common problem after high tibial osteotomy. It has been shown that lower limb rotation has an effect on the two‐dimensional measurement of lower limb alignment. Although alignment errors are known to occur due to limb rotation, the magnitude of this effect is unknown. Navigation systems allow for the measurments of coronal plane alignment and dynamically rotational and sagittal plane. Our study evaluated the effect of rotational leg movements on coronal plane alignment as determined by image‐free navigation. We hypothesized that a linear relationship exists between rotation and angular measurements. Eight cadavers were used, while three test conditions of the complete lower limbs were established: (1) solid knee arthrodesis, (2) provisional knee arthrodesis and (3) unconstrained knee conditions. Navigated measurements of coronal and sagittal lower limb axis were done initially without knee flexion for defined internal/external rotations of 5°, 10° and maximal values for all test series. Repeated test for the unconstrained knee included stepwise knee flexion of 5°, 10° and 20°. Statistical analysis comparing the test conditions 1, 2 and 3 and comparison between flexion movements of the unconstrained knee were done. Results revealed no significant differences between the different rotations of test condition 1 (mean 0.34°, SD 0.23, range, 0°–0.8°). Condition 2 similarly did not result in significant deviations (mean 0.51°, SD 0.24, range 0.1°–0.9°). Measurement deviations ranging from 0.4° to 4.3° were found for condition 3, the unconstrained knee. However, no statistically different testings from the arthrodesed knee were found ( P = 0.099–0.410). Knee flexion from 5°, 10° or 20°, showed significant deviations ( P < 0.05) for all rotations at all degrees of flexion. Rotation and flexion of 5° led to significant alignment errors of 3.4° and 2.8°, respectively, for internal and external rotations. Measurement failures due to the rotational movements of 1°–4° might add to additional sources of errors causing relevant under‐ or overcorrections of the mechanical leg axis. Discrepancies of the axis due to rotational movements as well as flexion of the knee joint can be avoided and corrected immediately with the help of navigation.

The aim of this study was to investigate, to what extent routine preoperative MRI scans could set the indications for knee arthroscopies and reduce the number of diagnostic arthroscopies. For this retrospective cohort study, 1,000 patients who had knee arthroscopies documented in 1994/1995 were compared with 1,000 patients that were treated in 2004/2005. The preoperative diagnoses that gave indications for knee arthroscopy were compared with the intraoperative findings. The congruence of preoperative diagnosis with the intraoperative findings was evaluated comparing both study populations. The number of patients who were referred to orthopaedic trauma surgeons with MRI increased from 24% to 56%. A high congruence of preoperative diagnosis and intraoperative findings was found in 49% in 1994/1995 and 55% in 2004/2005. However, regarding the most important outcome parameter, the number of diagnostic arthroscopies, no improvement was found (3% in both periods). The presented data suggests that MRI scans are not routinely necessary as an indication for knee arthroscopy, as clinical examination and plain radiograph are sufficient. However, MRI scans do allow a more detailed characterization of the expected findings and can therefore be helpful in therapy planning.

Purpose Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations. Methods In a controlled laboratory study, the patellar-, quadriceps- and hamstring tendons of 10 human cadavers (age: 49.2 ± 18.5 years) were used. An inside out press-fit fixation with a knot in the semitendinosus and gracilis tendons (SG) combined with an additional bone block, with two quadriceps tendon bone block grafts (QU) was compared with press-fit fixation of two bone patellar tendon bone block (PT) grafts in 30 porcine femora. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated. Results The maximum load to failure was 703 ± 136 N for SG fixation, 632 ± 130 N for QU and 656 ± 127 N for PT fixation. Stiffness of the constructs averaged 138 ± 26 N/mm for SG, 159 ± 74 N/mm for QU, and 154 ± 50 N/mm for PT fixation. Elongation during initial cyclical loading was 1.2 ± 1.4 mm for SG, 2.0 ± 1.4 mm for QU, and 1.0 ± 0.6 mm for PT (significantly larger for PT and QU between the first 5 cycles compared with cycles 15–20th, P  < 0.01). Conclusion All investigated double-bundle fixation techniques were equal in terms of maximum load to failure, stiffness, and elongation. Unlike with single-bundle press-fit fixation techniques that have been published, no difference was observed between pure tendon combined with an additional bone block and tendon bone grafts. All techniques exhibited larger elongation during initial cyclical loading. All three press-fit fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical.

Heat shock protein 72 (HSP-72) is a member of a superfamily of different proteins that are synthesized as a cytoprotective response following cellular stress. Mechanical strain is an important component in ligament and tendon healing. Up to the present point of time, the influence of mechanical strain on the expression of HSP-72 is unknown. Tendon fibroblasts from the patellar tendons of nine individuals were isolated and amplified in vitro. First, the effect of 15 or 60 min of heat exposition was studied immunohistochemically and by Western blotting. In a second experiment, the effects of 15 and 60 min of cyclic longitudinal stretching were investigated. Samples were taken after 2, 4 and 8 h. The heat exposition experiments indicate that HSP-72 accumulates in the nucleus and that there is a transient upregulation. This effect is more prominent after 60 min of heat exposure. The same reaction was found after stretching stimulation, however, to a lesser extent. There was a transient up regulation of HSP-72 after short-term stretching and a biphasic increase after 60 min of stretching. Upregulation of HSP-72 by heat and mechanical stress is a response in human fibroblasts which involves a nuclear translocation. The response differs with regard to the time points beyond 2 h after the application of either stress.