Postural Stability and Pedobarography After Reconstruction of Peroneus Brevis Tendon Split Lesion.

PURPOSE: Lesions of the peroneal tendons are frequently overseen after ankle sprain. The symptoms consist of stress-dependent pain that extends from the inframalleolar to the proximal part along the course of the peroneal tendons as well as ankle instability and soft-tissue swelling. In case of unsuccessful conservative treatment, surgical therapy is recommended. The aim of the study was to evaluate the clinical and functional outcome after open reconstruction of the peroneus brevis tendon. METHODS: 13 patients were included in this retrospective study. All of them received a single reconstruction of the peroneus brevis tendon in open technique. Postoperative results were evaluated with the AOFAS score, a functional and perdobargraphic analysis as well as measuring postural stability with the Biodex balance system. The participants were matched with a healthy control group according to age, sex and BMI. RESULTS: The results of the AOFAS score showed significantly convincing results in all subscores postoperatively. A bilateral comparison of the postural stability showed that the affected side had become functionally similar to the healthy side. No statistical significant difference was detected concerning both one-legged and two-legged standing with the control group. Pedobarographic results revealed no difference between the affected and contralateral side, as well as between the patients and the healthy control group. CONCLUSION: Open reconstruction of the peroneus brevis tendon leads to significant better postoperative results and can be recommended after unsuccessful conservative treatment as promising option.

Medial Open Wedge High tibial Osteotomy (MOWHTO) does not relevantly alter patellar kinematics: a cadaveric study.

PURPOSE: The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown. METHODS: Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two-sided p value of ≤ 0.05 was considered statistically significant. RESULTS: Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p < 0.001, respectively) compared to natural kinematics. CONCLUSIONS: Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.

Improved femoral component rotation in total knee arthroplasty: an anatomical study with optimized gap balancing.

INTRODUCTION: Surgically balanced total knee arthroplasties have shown improved functional and clinical outcomes. Two different alignment methods have been proposed, the measured resection technique which uses femoral landmarks on the one hand and the ligament balanced technique which uses spreaders on the other. As anatomical landmarks also vary widely, with regards to the tibial cut irrespective of the collateral ligaments, we hypothesized that anatomical landmarks are not suitable for ideal femoral component rotational alignment. MATERIALS AND METHODS: Ten cadaveric bilateral knees underwent TKA using a navigational device and a double tensiometer. By means of the navigational device, flexion gaps were balanced by femoral component size, rotation and flexion until a symmetric flexion and extension gap was obtained. Acquired femoral component rotation was compared to femoral landmarks (Whiteside Line, posterior condylar line and trans-epicondylar line). RESULTS: Using the Whiteside line, the posterior condylar line and the surgical trans-epicondylar line to identify femoral component rotation did not balance the flexion gap as well as navigation. Depending on the parameter, deviations in femoral rotation of up to 6° were observed compared to the gap balancing technique. Furthermore, large deviations between these landmarks were observed. CONCLUSION: Based on this study flexion gap balancing can be better optimized using ligament balancing technique. As this technique is highly dependent on the proximal tibial cut, we do recommend the use of navigational devices, which additionally assure a neutral leg alignment.

A novel device for greater precision and safety in open-wedge high tibial osteotomy: cadaveric study.

INTRODUCTION: The complications of the open-wedge osteotomy technique (slope, hypo- and hypercorrection and fractures) are related to difficulties in the control of the open-wedge angle during surgery. MATERIALS AND METHODS: In this cadaveric study, we evaluated the safety and precision of a novel system, the Realignment High Control System (RHC), in the correction of knee mechanical axis and slope. The RHC has a fixation plate coupled to a dynamic device that opens the osteotomy continuously, allowing plate fixation before osteotomy wedge opening. RESULTS: All procedures were easily performed, with no fractures. The openings equaled the indicated by the navigation system for 7.5° and 10°, and for 5°, there was a statistically, although not clinically significant, difference of 0.6°. The slope shown by the RHC setting and in the navigation system was significantly different for the 10° setting only, with a mean difference of 0.563°. CONCLUSIONS: RHC facilitates the surgical technique of high tibial osteotomy, with gradual wedge opening, precise correction of the mechanical axis, and appropriate control of the tibial slope, even with larger openings.

Kinematic alignment in total knee arthroplasty leads to a better restoration of patellar kinematics compared to mechanic alignment.

PURPOSE: The influence of different implantation techniques in TKA on tibiofemoral kinematics was analysed in few investigations so far. However, the influence on patellar kinematics remain unclear. The aim of the present investigation was to compare patellar kinematics of the natural knee with those of knees after both kinematically and mechanically aligned TKAs. METHODS: Patellar kinematics of ten cadaveric knees before and after TKAs implanted using both a kinematic and mechanic alignment technique were investigated and compared using a commercial optical computer navigation system. RESULTS: There was a statistically significant difference between natural patellar kinematics and both implantation techniques analysing mediolateral shift. Patellar lateral tilt showed significant better results in the kinematically compared to the mechanically aligned TKAs. In terms of patella rotation, the patella of both mechanically and kinematically aligned TKAs showed significant higher values for external rotation compared to the natural knee. Regarding epicondylar distance again a significant better restoration of natural kinematics could be found in the kinematically aligned TKAs. CONCLUSION: Kinematically aligned TKAs showed a better overall restoration of patellar kinematics compared to a conventional mechanical alignment technique. In terms of clinical usefulness, the present study highlights the potential benefit for clinical outcome using a kinematically aligned implantation technique in TKA to achieve a better restoration of natural patellofemoral kinematics.

Kinematic component alignment in total knee arthroplasty leads to better restoration of natural tibiofemoral kinematics compared to mechanic alignment.

PURPOSE: Kinematically aligned total knee arthroplasty is associated with superior pain relief, increased flexion and a more normal feeling knee. It was hypothesized that due to restoring the knee's natural anatomy, kinematically aligned knees show more physiological tibiofemoral kinematics than mechanically aligned knees. METHODS: Investigations were performed in nine healthy cadaveric knees of whole bodies fixed by the Thiel method. Tibiofemoral kinematics of healthy knees and after kinematically and mechanically aligned total knee arthroplasty were assessed between 0° and 90° of flexion by a navigational device. RESULTS: Regarding tibial internal rotation or femoral roll back, respectively, kinematically aligned total knee arthroplasties showed no significant differences between 0° and 70° of flexion in comparison to knees before total knee arthroplasty. In contrast, mechanically aligned total knee arthroplasties showed significant changes between 10° and 90° of flexion. Kinematically aligned knees showed a significant changed abduction/adduction between 20° and 70° of flexion, mechanically aligned knees within 20° and 90° of flexion. CONCLUSION: In the present study setting kinematically aligned total knee arthroplasties showed more natural and physiological tibiofemoral kinematic pattern with regard to tibial internal rotation or femoral rollback, respectively, and tibial adduction than mechanically aligned total knee arthroplasties. While these results may support promising early clinical results of kinematical alignment proposing a better function, long-term results especially implant survival need to be awaited.

Reproducibility of navigation based kinematic analysis of the knee - A cadaveric investigation.

PURPOSE: Several navigation-based kinematic studies of the knee have been published recently, but little information is available about reproducibility and reliability of the acquired data. The aim of the present study first is to determine reproducibility and reliability of kinematical measurements of healthy knees and knees after TKA (total knee arthroplasty) with regards to rotational and translational measurement parameters. Second the mathematical background, applicability, and limitations of investigating navigation-based kinematics should be compiled. METHODS: Using cadavers fixed by the Thiel method, in ten knees reproducibility of obtained angular and translational kinematic parameters were investigated before and after total knee arthroplasty. For this reason agreement of obtained data of a first and a second movement cycle and the same after a surgical intervention was assessed using a commercially available navigational device. RESULTS: For both angular and translational parameters in healthy knees and knees after total knee arthroplasty mean differences between measured parameters of the first and second movement cycle and after surgical intervention of less than 0.5° or millimeters (standard deviation 1.3 or less) or a inter class correlation of 0.92 and more, respectively, was found. DISCUSSION: Use of a commercial navigation system allows highly accurate investigations of knee kinematics in cadavers before and after TKA. This technique, which does not require any specific technical knowledge of the investigator, is in accordance with current accepted biomechanical methods.

Rotation of intramedullary alignment rods affects distal femoral cutting plane in total knee arthroplasty.

PURPOSE: Intramedullary rods are widely used to align the distal femoral cut in total knee arthroplasty. We hypothesised that both coronal (varus/valgus) and sagittal (extension/flexion) cutting plane are affected by rotational changes of intramedullary femoral alignment guides. METHODS: Distal femoral cuts using intramedullary alignment rods were simulated by means of a computer-aided engineering software in 4°, 6°, 8°, 10°, and 12° of valgus in relation to the femoral anatomical axis and 4° extension, neutral, as well as 4°, 8°, and 12° of flexion in relation to the femoral mechanical axis. This reflects the different angles between anatomical and mechanical axis in coronal and sagittal planes. To assess the influence of rotation of the alignment guide on the effective distal femoral cutting plane, all combinations were simulated with the rod gradually aligned from 40° of external to 40° of internal rotation. RESULTS: Rotational changes of the distal femoral alignment guides affect both the coronal and sagittal cutting planes. When alignment rods are intruded neutrally with regards to sagittal alignment, external rotation causes flexion, while internal rotation causes extension of the sagittal cutting plane. Simultaneously the coronal effect (valgus) decreases resulting in an increased varus of the cutting plane. However, when alignment rods are intruded in extension or flexion partly contradictory effects are observed. Generally the effect increases with the degree of valgus preset, rotation and flexion. CONCLUSION: As incorrect rotation of intramedullary alignment guides for distal femoral cuts causes significant cutting errors, exact rotational alignment is crucial. Coronal cutting errors in the distal femoral plane might result in overall leg malalignment, asymmetric extension gaps and subsequent sagittal cutting errors.

Are We Subluxating Knees in Total Knee Arthroplasty? A Cadaveric Investigation.

BACKGROUND: In comparison to coronal, sagittal, and rotational alignment, translational alignment parameters have been widely neglected in total knee arthroplasty (TKA) so far. As there is a certain variable range of possible component placement in mediolateral, ventrodorsal, and proximodistal direction, we hypothesized that relative positions between the femoral and tibial bones are changed after TKA, resulting in a subluxation of knees. METHODS: In 10 knees of Thiel-embalmed whole body cadavers, the relative position between the femur and the tibia during passive flexion was measured before and after TKA by means of a navigational device. RESULTS: After TKA, in extension, femoral bones in average shifted 5.3 mm (standard deviation [SD] = 4.0, P = .002) laterally and 2.4 mm (SD = 3.1, P = .038) proximally in extension which, however, decreased throughout flexion. Furthermore, the ventrodorsal femoral position was altered, resulting in a slight relative dorsal shift (2.6 mm, SD = 4.5, P = .099) in extension, which continuously changed into a ventral shift (2.6 mm, SD = 4.3, P = .087) during flexion. CONCLUSION: The present investigation reveals changed translational parameters between the tibia and the femur after TKA. The resulting subluxation of the knee may be responsible for changed kinematic patterns. These changes in tibofemoral position should be considered in future biomechanical studies. Main reasons for this effect might be a noncentral placement of tibial and femoral implants in relation to the proximal tibial and distal femoral anatomy, obscured intraoperative articular geometry, symmetric implants, and operative techniques. Smaller steps between different component sizes, asymmetric tibial implant design, or individual (anatomic) implants could help to minimize subluxation in TKA.

Influence of Component Rotation in Total Knee Arthroplasty on Tibiofemoral Kinematics-A Cadaveric Investigation.

BACKGROUND: Physiological tibiofemoral kinematics have been shown to be important for good knee function after total knee arthroplasty (TKA). The purpose of the present study was to investigate the influence of component rotation on tibiofemoral kinematics during knee flexion. We asked which axial component alignment best reconstructs physiological tibiofemoral kinematics and which combinations should be avoided. METHODS: Ten healthy cadaveric knees were examined. By means of a navigational device, tibiofemoral kinematics between 0° and 90° of flexion were assessed before and after TKA using the following different rotational component alignment: femoral components: ligament balanced, 6° internal, 3° external rotation, and 6° external rotation in relation to the posterior condylar line; tibial components: self-adapted, 6° internal rotation, and 6° external rotation. RESULTS: Physiological tibiofemoral kinematics could be partly reconstructed by TKA. Ligament-balanced femoral rotation and 6° femoral external rotation both in combination with 6° tibial component external rotation, and 3° femoral external rotation in combination with 6° tibial component internal rotation or self-aligning tibial component were able to restore tibial longitudinal rotation. Largest kinematical differences were found for the combination femoral component internal and tibial component external rotations. CONCLUSION: From a kinematic-based view, surgeons should avoid internal rotation of femoral components. However, even often recommended combinations of rotational component alignment (3° femoral external and tibial external rotation) significantly change tibiofemoral kinematics. Self-aligning tibial components solely restored tibiofemoral kinematics with the combination of 3° femoral component of external rotation. For the future, navigational devices might help to axially align components to restore patient-specific and natural tibiofemoral kinematics.

Off-loading strategies in diabetic foot syndrome-evaluation of different devices.

INTRODUCTION: Diabetic foot syndrome is one of the most dreaded complications in diabetes mellitus. The purpose of this study was to assess the value of different offloading devices compared to walking in barefoot condition and in normal shoes both in healthy subjects and in patients with diabetes and neuropathy. METHODS: Twenty patients with diabetes and polyneuropathy and ten healthy probands were included. Pedobarographic examination was performed in barefoot condition, with sneakers, postoperative shoes, Aircast® Diabetic Pneumatic Walker™ and VACO®diaped. In the diabetic group, a total contact cast was additionally tested. RESULTS: The most effective reduction of force was achieved by TCC (75%) and VACOdiaped (64.3%) with the VACO®diaped resulting in the most homogeneous distribution of forces all over the foot. DISCUSSION/CONCLUSION: A customized device like the TCC is still the most proven offloading device. However, a removable cast walker being based on vacuum pads and a cushioning sole, provides better results concerning force distribution.

Postural stability after patient-specific interpositional knee spacer or total knee arthroplasty: a comparative study.

PURPOSE: Total knee arthroplasty provides excellent results concerning functional demands, patient satisfaction and range of motion. Short-term results after implantation of patient-specific knee spacers also show encouraging results. We hypothesised that patient-specific interpositional devices provide better proprioception and postural stability by preserving the whole bone stock and both cruciate ligaments. METHODS: In this study we compared functional results, proprioception and postural stability 16 months after 20 consecutive patient-specific interpositional device implantations of the knee (group A) and 20 consecutive total knee arthroplasties (group B). Patients were evaluated using the Knee Society Score (KSS) and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Postural stability was analysed during single leg stance on a force platform (Biodex). RESULTS: There were no significant differences between both groups concerning functional results 16 months after the procedure. Concerning postural stability, significant differences were found between both groups. Comparing the operated-on and non-operated-on sides in single leg stance, the operated-on leg gained the same stability as the non-operated-on side in both groups. CONCLUSIONS: The successful treatment of knee osteoarthritis can restore postural stability to the level of the unaffected side-independent from the implanted devices and with preservation of soft tissue and bone stock. Superior postural stability in joint-preserving patient-specific interpositional knee devices compared with total knee arthroplasty had to be attributed to the different age of both groups.

Presence of rotational errors in long leg radiographs after total knee arthroplasty and impact on measured lower limb and component alignment.

PURPOSE: Rotation of the lower limb in weight bearing long leg radiographs has a great impact on measured component and lower limb alignment parameters. We asked which rotational errors of long leg radiographs are present in a high volume centre and which radiological and clinical consequences arise regarding measured coronal component and lower limb alignment after total knee arthroplasty. METHODS: In 100 long leg radiographs coronal femoral and tibial component alignment and hip knee ankle angle (HKA) were measured. Present rotational errors in long leg radiographs were determined by fibular overlap and its impact on alignment parameters calculated. RESULTS: A mean internal rotation of 8.1° (9.3 SD) with a range between 36° of internal and 16° of external rotation was found in long leg radiographs. This resulted in mean differences between measurements before and after rotational correction regarding femoral and tibial component alignment and HKA of 0.6-0.8° (range 3.5° valgus and 1.6° varus error). Clinically, 11 out of 100 patients were wrongly assigned to either mal- or well-alignment (neutral mechanical alignment within ±3° varus or valgus). CONCLUSION: Surgeons should be aware of potential rotational errors in long leg radiographs after total knee arthroplasty resulting in wrong measurements. In case of rotational errors, radiographs should be repeated or rotational corrections calculated. For study purposes only radiographs after rotational correction should be accepted.

Clinical, radiological and survivorship results after ten years comparing navigated and conventional total knee arthroplasty: a matched-pair analysis.

PURPOSE: Our aim was to compare the long-term outcome between navigated and conventional total knee arthroplasty (TKA), which is currently not known. METHODS: Long-term survivorship, clinical scores and radiographic results of a matched-pair group of 350 patients (350 knees) treated with navigated (n = 157) or conventional (n = 188) TKA for osteoarthritis over a period of 11 years were reviewed retrospectively. RESULTS: The mean clinical follow-up was ten years. There were no clinically relevant differences with respect to any clinical outcome, patient satisfaction or pain between the two groups. Coronal leg alignment was closer (1.7-3.1°) to the neutral mechanical axis in the navigated group compared with the conventional group (2.6-4.7°). A total of 12 knees (6.4%) in the conventional group and three (1.9%) in the navigated group underwent revision surgery (p = 0.04), resulting in an absolute risk reduction of 4.5% for revision surgery by using navigation. Using any revision as an end point, the ten-year Kaplan-Meier survivorship was 98.1% in the navigated and 92.5% in the conventional group. CONCLUSIONS: Navigated TKA improves implant survivorship compared with conventional TKA.

Stability of capsule closure and postoperative anterior knee pain after medial parapatellar approach in TKA.

PURPOSE: Anterior knee pain after total knee arthroplasty (TKA) remains a widely discussed postoperative complication. In contrast to sports traumatology, the role of the dissected medial patellofemoral ligament (MPFL) using a medial parapatellar approach in TKA has not been discussed so far. In the present study, it was hypothesized that the attempted repair of the MPFL in TKA by simple closure of the joint capsule may not be successful in some cases, causing anterior knee pain. Furthermore, it was hypothesized, that the success of repair might be influenced by femoral component rotation. METHODS: Forty patients received their TKA in a ligament-balanced and forty patients in a conventional measured-resection technique. After implantation of the TKA using a medial parapatellar approach, two titan clips were attached on both sides of the capsule incision. 3 days and 3 months after surgery, the dehiscence of the two clips was measured on skyline patella radiographs; additionally patellar tilt, shift, the Knee Society Score and the Feller Score were obtained. RESULTS: 48 patients showed an increase of capsule dehiscence. Patients with a capsule dehiscence of more than 4 mm showed significantly less improvement in the Feller score 3 months postoperatively than patients with a capsule dehiscence ≤4 mm. Regarding the radiological measurements and the clinical outcome, no significant difference between the ligament-balanced and the measured-resection group was found. CONCLUSIONS: The present results suggest that the successful repair of the MPFL after using a medial parapatellar approach in TKA could reduce the high rate of postoperative anterior knee pain. Furthermore, the appearance of capsule dehiscence and anterior knee pain does not seem to be dependent on the used operative technique.

Significant influence of rotational limb alignment parameters on patellar kinematics: an in vitro study.

PURPOSE: Component malrotation has a major impact on patellar kinematics in total knee arthroplasty. The influence of natural rotational limb alignment on patellar kinematics is unclear so far. Based on recent clinical investigations, we hypothesized that rotational limb alignment significantly influences patellar kinematics. METHODS: Patellar kinematics of ten cadaveric knees was measured using computer navigation during passive motion. Data were correlated with different rotational limb alignment parameters of preoperative CT scans. RESULTS: Femoral antetorsion showed a significant influence on patellar rotation, while tibial tubercle-posterior cruciate ligament distance additionally displayed a significant influence on patellar mediolateral shift (p < 0.05). Femoral posterior condylar angle was sensitive to patellar epicondylar distance, rotation and tilt (p < 0.05). Patellar rotation was influenced by five out of eight rotational limb alignment parameters (p < 0.05). CONCLUSIONS: Rotational limb alignment should be paid more attention in terms of clinical evaluation of patellar tracking and future biomechanical and clinical investigations.

Changes in sagittal component alignment alters patellar kinematics in TKA: an in vitro study.

PURPOSE: Patellar maltracking due to incorrect component alignment is considered as a main reason for anterior knee pain after total knee arthroplasty (TKA). In contrast to coronal and axial component placement, the influence of sagittal component alignment on patellar kinematics has not been investigated so far. METHODS: In ten lower cadaveric limbs, TKAs were implanted using a commercial computer navigation system. In six knees, the femoral component was aligned in 5° and in four knees in 0° of flexion, respectively. Patellar kinematics were registered by means of a computer navigation system using an additional patella tracking array and correlated with femoral and tibial sagittal component alignment. RESULTS: Sagittal component alignment significantly altered patellar mediolateral shift (p < 0.05). In contrast, patellar epicondylar distance, rotation and tilt were not significantly influenced. CONCLUSIONS: Sagittal component alignment in TKA has a major impact on patellar kinematics and should therefore be considered while addressing tibiofemoral kinematics intraoperatively.

Appropriate sagittal femoral component alignment cannot be ensured by intramedullary alignment rods.

PURPOSE: The intraoperative sagittal cutting block alignment when intramedullary alignment rods are used was investigated. Its absolute orthogonal orientation in relation to the mechanical femoral axis should be analysed. It was hypothesized that (1) alignment rods do not ensure a desired deviation within a range between 0° and 3° flexion as it has been shown to be favourable for clinical and functional outcome. Further, the degree of flexion cannot be (2) foreseen by the surgeon or (3) estimated by clinical or radiological parameters. METHODS: Forty knees allocated to total knee arthroplasty were included. The distal femoral cutting block was aligned using an intramedullary rod. By means of a navigation device, the sagittal alignment of the cutting block in degrees of flexion was measured. RESULTS: The mean measured flexion of the cutting block was 4.4° (3.6 SD). Twenty-five per cent (10/40) of the values were within a corridor between 0° and 3° of flexion. The mean difference between expected and measured flexion was -1.5° (-7.6 to 4.7 95 % limits of agreement). The dorsoventral diameter of the distal femur showed a significant influence on measured flexion (R (2) = 0.112, p = 0.035). CONCLUSION: Intramedullary alignment rods used in the present study do not ensure a distal cutting block alignment between 0° and 3° of flexion in relation to the femoral mechanical axis. The extent of flexion could not be foreseen either by the surgeon. The dorsoventral diameter of the distal femur correlated with measured flexion. However, only limited data is available on influence of femoral component flexion on implant failure or clinical and functional outcome. LEVEL OF EVIDENCE: Diagnostic study, Level II.