Establishing a New Patient-Specific Implantation Technique for Total Ankle Replacement: An In Vitro Study.

BACKGROUND: Revision rates after total ankle replacements (TARs) are higher compared with other total joint replacements. The present study aimed to establish a new patient-specific implantation (PSI) technique for TAR. MATERIAL AND METHODS: A total of 10 complete Caucasian cadaver legs had whole leg computed tomography scans. The individual geometrical ankle joint axis was determined, and based on this axis, the position of the prosthesis was planned. We assessed prosthesis placement, guiding block position, and preoperative and postoperative ankle rotational axes. RESULTS: The guiding block position interobserver reliability was 0.37 mm 0.45 (mean ± SD) for the tibial guiding block. The value for the first talar guiding block was 1.72 ± 1.3 mm and for the second talar guiding block, 0.61 ± 0.39 mm. The tibial slope as well as the frontal angles of the anatomical tibial axis compared to the tibial and talar articular surfaces showed no statistically relevant differences with numbers available. The deviation of the assessed preoperative joint axis to the postoperative joint axis was 14.6° ± 7.8. CONCLUSION: The present study describes the results of an establishing process of a new PSI technique for TAR. The reliability of guiding block positioning and, thereby, prosthesis placement is sufficient. LEVEL OF EVIDENCE: Biomechanical study.

Foot and Ankle Surgical Incision Closure With Three Different Materials.

There is no clear recommendation for wound closure material in foot and ankle surgery. Thus, we hypothesized that there was no difference in clinical outcomes among 3 suture materials, namely, absorbable sutures, nonabsorbable sutures, and metallic staples. This study compared the 3 materials for wound closure in foot and ankle surgery. In this prospective randomized study, 124 patients were randomly divided into the nonabsorbable suture group, absorbable suture group, and staple group. ASEPSIS score, Hollander Wound Evaluation Scale, and numerical rating scale (regarding pain and satisfaction) were collected at first dressing changes, suture removal, and 6 weeks after surgery. Suture time and incision length were recorded. No significant differences were detected for the ASEPSIS and Hollander Wound Evaluation Scale scores. There was significantly more pain after 6 weeks in the nonabsorbable suture group. The closure time (13 s/cm) with staples was significantly lower in the nonabsorbable suture group than in the other groups. Regardless of wound closure material, male sex and obesity appeared to be associated with a higher risk for the occurrence of wound complications. The 3 suture materials showed no significant differences regarding the frequency of wound complications. Staples and absorbable sutures should therefore be considered in the repertoire of suture materials used in foot and ankle surgery.

Knee disarticulation following oncologic total knee arthroplasty: A 5-year follow-up case report.

BACKGROUND: The present case report describes the 5-year follow-up results of an atypical knee disarticulation of a man previously treated with an oncologic total knee arthroplasty due to an Ewing sarcoma. METHODS: The patient presented an aseptic loosened tibial component of a tumor prosthesis system and requested final amputation, as he had previously suffered from five revision surgeries. To encourage the most functional outcome regarding an exoskeletal prosthesis, we decided to disarticulate the knee joint while retaining the currently fixed femoral component to create a full end-bearing stump. FINDINGS: The patient could be mobilized as a functional knee disarticulated amputee. Seven months after amputation, he showed a slightly less symmetrical gait compared to the preoperative status (preoperative mean Symmetry Index: 0.984 for kinematics and 0.940 for kinetics, 7-month postoperative Symmetry Index: 0.858 and 0.915). At the 5-year follow-up, the femoral component is still stably fixated and shows no loosening signs. In addition, the Symmetry Index increased to 0.908 and 0.949. INTERPRETATION: Even after 5 years, the presented amputation appears to be consistent with "conventional" knee disarticulation. The femoral component still withstands the altered loads and the patient shows a further improved gait pattern.

LOQTEQ® VA Periprosthetic Plate-A New Concept for Bicortical Screw Fixation in Periprosthetic Fractures: A Technical Note.

Internal fixation using angle stable plates is the treatment standard in periprosthetic fractures around stable implants. To provide instant postoperative full weight-bearing, bicortical screw fixation is advisable but often surgically demanding. This work presents the first clinical results of the LOQTEQ® VA Periprosthetic Plate (aap Implantate AG, Berlin, Germany), a new plate system to simplify screw placement around implants. This plate system uses insertable hinges that allow for variable angle screw anchorage. Data of 26 patients with a mean age of 80 years and a mean follow-up of 13.9 months were retrospectively collected. Patients were clinically and radiologically examined. Bony union was achieved in 14 out of 15 patients with no signs of non-union or implant loosening. One patient, however, presented with implant failure. Clinical scores demonstrated acceptable results. Since the hinge plates are easy to apply, the first results are promising.

Peri- and Interprosthetic Femoral Fractures-Current Concepts and New Developments for Internal Fixation.

Treatment of peri- and interprosthetic fractures represents a challenge in orthopedic trauma surgery. Multiple factors such as osteoporosis, polymedication and comorbidities impede therapy and the rehabilitation of this difficult fracture entity. This article summarizes current concepts and highlights new developments for the internal fixation of periprosthetic fractures. Since the elderly are unable to follow partial weight bearing, stable solutions are required. Therefore, a high primary stability is necessary. Numerous options, such as new angular stable plate systems with additional options for variable angle screw positioning, already exist and are in the process of being further improved. Lately, individually produced custom-made implants are offering interesting alternatives to treat periprosthetic fractures.

Bicompartmental, medial and patellofemoral knee replacement might be able to maintain unloaded knee kinematics.

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are standard procedures for treating knee joint arthritis. Neither UKA nor TKA seems to be optimally suited for patients with bicompartmental osteoarthritis that affects only the medial and patellofemoral compartments. A bicompartmental knee arthroplasty (BKA) was designed for this patient group. This study aimed to compare the effectiveness of a BKA and TKA in restoring the kinematics of the knee joint. MATERIALS AND METHODS: In this in vitro study, three types of knee arthroplasties (BKA, posterior cruciate ligament-retaining, and posterior cruciate ligament-resecting TKA) were biomechanically tested in six freshly frozen human cadaveric specimens. Complete three-dimensional kinematics was analyzed for each knee arthroplasty during both passive and loaded conditions in a validated knee kinematics rig. Infrared motion capture cameras and retroreflective markers were used for recording data. RESULTS: No significant differences could be found between the three types of arthroplasties. However, similar kinematic changes between BKA and a native knee joint were documented under passive conditions. However, in a weight-bearing mode, a significant decrease in femoral rotation during the range of motion was found in arthroplasties compared to the native knee, probably caused by contraction of the quadriceps femoris muscle, which leads to a decrease in the anterior translation of the tibia. CONCLUSIONS: Kinematics similar to that of the natural knee can be achieved by BKA under passive conditions. However, no functional advantage of BKA over TKA was detected, which suggests that natural knee kinematics cannot be fully imitated by an arthroplasty yet. Further prospective studies are required to determine the anatomic and design factors that might affect the physiologic kinematics.

Manipulation under anesthesia as a therapy option for postoperative knee stiffness: a retrospective matched-pair analysis.

INTRODUCTION: Due to demographic changes, total knee arthroplasty (TKA) is one of the most frequently performed orthopedic surgeries. Therapies for associated postoperative complications, such as postoperative knee stiffness (PKS), are becoming increasingly important. The aim of this retrospective matched-pair analysis was to evaluate mid-term-results following manipulation under anesthesia (MUA). MATERIALS AND METHODS: Fifty-one patients with PKS were evaluated and 51 matched-pair patients without PKS after primary TKA were chosen for the control group. In addition to the range of motion, the functionality was recorded by Knee Society Score (KSS), Western Ontario and Mc Masters Universities Osteoarthritis Index (WOMAC), and Short-Form-12 Questionnaire (SF-12). Experience of pain was mapped using a 10-point Numeric Rating Scale (NRS), and the analgesic requirement was mapped using the WHO step scheme. A final follow-up examination was conducted approximately three years after TKA. To evaluate potential risk factors for the development of PKS, TKA alignment was measured via postoperative X-ray images. RESULTS: Improvement of the average knee flexion of 35.7° and total flexion of 107.4° was detected in PKS patients after MUA. The flexion of the control group was 112.4°; no significant between-group difference was present regarding prosthesis type, sex, age and BMI. Regarding KSS, WOMAC, and SF-12, the MUA cohort achieved statistically-relevant lower overall scores than the control group, p = 0.006, p = 0.005, p = 0.001, respectively. Significantly higher experiences of pain and a higher need for analgesics in MUA patients were reported (p = 0.001 and p < 0.001, respectively). Radiological evaluation of the prosthesis alignment did not show any differences between the two groups. CONCLUSIONS: MUA can improve mobility after PKS, whereby MUA seemed to be a functional therapy option for PKS. Compared to the control group, the MUA group showed lower functional values and an increased experience of pain. A correlation between prosthesis malalignment and MUA could not be detected radiologically. Further studies are necessary to investigate the reasons for PKS.

Short term results of dynamic splinting for hallux valgus - A prospective randomized study.

Background Hallux valgus is a common diagnosis in orthopedics. Only a few studies have analyzed the effects of conservative therapy. Therefore, the current study analyzed the effect of a dynamic hallux valgus splint. Methods Seventy patients were included in this prospective randomized trial. Patients with a hallux valgus were treated using a dynamic splint or underwent no treatment. Clinical and radiological parameters were evaluated. Results We found no significant changes in hallux valgus angle, intermetatarsal I-II angle, AOFAS score, FAOS or SF-36 score between the groups. However, a significant between-group difference was found for pain during walking and running and in the FAOS subscale for pain and pain at rest at follow-up. Conclusions Wearing a dynamic hallux valgus splint does provide some pain relief in patients with a symptomatic hallux valgus, but showed no effect on hallux valgus position. Level of evidence: 1.

Relevance of SPECT-CT in Complex Cases of Foot and Ankle Surgery: A Comparison With MRI.

BACKGROUND: Finding the right diagnoses in patients with complex foot and ankle disorders can be challenging. Single-photon emission computed tomography and computed tomography (SPECT-CT) has shown to be feasible in foot and ankle surgery. The aim of this study was to evaluate the reliability and accuracy of SPECT-CT and thereby its impact on final treatment decision compared with magnetic resonance imaging (MRI). METHODS: A retrospective study was performed on 49 patients treated at our institution. Experienced foot and ankle surgeons independently, and blinded, analyzed clinical data and radiographs together with MRI, SPECT-CT, or a combination of both. Based on the determined final treatment decision Cohen's kappa values were calculated to illustrate interrater and intrarater reliability. RESULTS: The kappa values for interrater reliability were higher for SPECT-CT at .68 and MRI + SPECT-CT at .71 compared to 0.38 for MRI alone (P < .05). The kappa values for intrarater reliability of MRI + SPECT-CT were higher at .75 compared with SPECT-CT alone at .67 (P < .05) and MRI at .35 (P < .01). CONCLUSION: We found a higher interrater and intrarater reliability for SPECT-CT compared with MRI alone for diagnosing complex foot and ankle pathologies. SPECT-CT has a high impact on final treatment decision. The main indications are bony pathologies with diagnostic uncertainty especially in closely adjacent structures as the joints of the midfoot, occult coalitio, stress fractures, verification or exclusion of nonfusion, periprosthetic disorders after total ankle replacement and osteochondral lesion in cases of combined pathologies.Levels of Evidence: Level IV: Retrospective study.

Outcomes of Evans Versus Hintermann Calcaneal Lengthening Osteotomy for Flexible Flatfoot.

BACKGROUND: Evans (E) and Hintermann (H) lateral lengthening calcaneal osteotomies (LLCOTs) are commonly used to correct flexible flatfoot deformities. Both methods are well accepted and produce good clinical results. The aim of this study was to compare the postoperative outcomes of both osteotomies. METHODS: We retrospectively examined 53 patients with flatfoot deformities, who received surgery between October 2008 and March 2014. Seventeen E-LLCOT and 36 H-LLCOT procedures were performed during this time period, with a mean follow-up of 67.7 ± 20.6 and 40 ± 12.9 months, respectively. Data were collected using clinical and radiological examination, as well as clinical scores (Foot and Ankle Outcome Score [FAOS], University of California at Los Angeles [UCLA] activity score, numerical rating scale [NRS], and the Short-Form 36-item Health Survey [SF-36]) during regular follow-up. RESULTS: For both groups of patients, the FAOS score, pain-NRS, and SF-36 improved significantly following surgery ( P < .05). The talus-second metatarsal angle, talonavicular coverage, and naviculocuneiform overlap showed significant correction ( P < .05). Postoperatively, radiographic degenerative changes were detected in the calcaneocuboid (CC) and subtalar joint in both groups of patients: 41% and 18% after E-LLCOT compared with 25% and 14% after H-LLCOT, although these changes did not have any clinical relevance ( P < .05). No secondary arthrodesis was necessary. There were no significant differences in the clinical or radiological outcome parameters when compared between the 2 groups. CONCLUSION: Both surgical techniques resulted in a significant improvement of clinical outcome scores and led to good radiological correction of flatfoot deformities. It appears that the CC joint develops less degenerative changes following the H-LLCOT procedure. LEVEL OF EVIDENCE: Level III, comparative series.

The prevalence of osteoarthritis: Higher risk after transfemoral amputation?-A database analysis with 1,569 amputees and matched controls.

BACKGROUND: Several studies have shown that patients with a unilateral amputation have an increased risk of developing osteoarthritis (OA) in the knee of their sound leg. OBJECTIVE: The first objective was to investigate whether amputees are more frequently affected by gon-, cox- or polyarthritis as well as back pain or spinal disorders. We hypothesized that mobile and active transfemoral amputees more often experience OA and spinal disorders than non-amputees. The second objective was to compare the mean age of the patients with OA. PATIENTS: Patients with a unilateral transfemoral amputation (n = 1,569) and five abled-body control groups (each n = 1,569) matched in terms of age and gender resulting in total of 9,414 participants. METHODS: Groups were analyzed regarding the prevalence of six selected diagnoses regarding musculoskeletal disorders. RESULTS: A significantly decreased prevalence of OA and specific disorders of the spine in transfemoral amputees compared to a control group was found. The amputees with OA are significantly younger than patients with OA in the control group. CONCLUSION: The results from the presented study contradict previously published literature. Apparently circumstances of life play an important role, like physical work and strenuous activities which are likely to be underrepresented in the amputee group. The results of the study need to be used cautiously due to the major limitation of the study which is the lack of detail in individual patients caused by the methodology.

The geometrical axis of the talocrural joint-Suggestions for a new measurement of the talocrural joint axis.

BACKGROUND: Despite intensive research there is no consensus about the talocrural joint axis. The aim of the present study is a new method to determinate the geometric rotational axis of the talocrural joint. METHODS: We analyzed 98 CT-scans of full cadaver Caucasian legs. We generated three-dimensional reconstruction models of the talus. A best fitting cone was orientated to the talar articular surface. The geometric rotational axis was defined to be the axis of this cone. RESULTS: The geometric rotational axis of the talocrural joint is orientated from lateral-distal to medial-proximal (85.6°±10 compared to anatomical tibial axis in torsional plane), from posterior-distal to anterior-proximal (81.43°±44.35 compared to anatomical tibial axis in sagittal plane) and from posterior-medial to anterior-lateral (169.2°±5.91 compared to intermalleolar axis in axial plane). CONCLUSIONS: The consideration of our results might be helpful for better understanding of ankle biomechanics.

Ankle morphometry based on computerized tomography.

BACKGROUND: Thorough understanding of the morphometry of the ankle joint is crucial to optimize conservative and operative therapy of ankle joint disorders. Despite recent improvements, basic anatomic and biomechanical correlations of the ankle joint including the orientation of the ankle joint axis and joint morphology as its key biomechanical features are not sufficiently recorded to date. The aim of this study was the evaluation of the ankle morphometry to gain information about the ankle joint axis. MATERIAL AND METHODS: In this study 98 high-resolution CT-scans of complete Caucasian cadaver legs were analysed. Using the software Mimics and 3-Matic (Materialize) 22 anatomic parameters of the talocrural joint were assessed, including the length, width and surface area of the tibial and talar articular areas. Additionally, the radii of the articular areas, the medial distal tibial angle and the height of the talar dome were determined. RESULTS: The radius of the central trochlea tali was 44.6±4.1mm (mean±SD). The central trochlea tali arc length was 40.8±3.0mm and its width was 27.4±2.5mm. Additionally we determined 47.0±4.4mm for the tibial sagittal radius, 27.6±3.0mm for the tibial arc length and 27.4±2.5mm for the central tibial width. CONCLUSION: The present study describes the three-dimensional morphometry of Caucasian ankle joints in detail. This dimensional analysis of the ankle joint will inform the development and placements of implants and prostheses.

Comparison of Anatomic Structures at Risk With 2 Lateral Lengthening Calcaneal Osteotomies.

BACKGROUND:: Lateral lengthening calcaneal osteotomies (LLCOT) are commonly used to treat flexible pes planovalgus deformity. Different operative techniques have been described. The aim of this study was to examine which anatomic structures were affected by 2 different osteotomy techniques. METHODS:: Two experienced foot and ankle surgeons each performed an Evans (E)- or Hintermann (H) osteotomy on 7 cadaver feet. The mean age of the donors was 80.4 ± 4.4 years. Eight left and 6 right feet were prepared. Previously identified structures at risk were prepared and evaluated. RESULTS:: After H-LLCOT, there was no damage of the peroneus longus tendon, whereas after E-LLCOT, damage was noted in 1 case (14.3%). The peroneus brevis tendon was once cut after H-LLCOT and eroded after E-LLCOT. In one cadaver, the sural nerve was partially damaged after H-LLCOT but in no case after E-LLOCT. The calcaneal anterior and medial articular facets were intact after H-LLCOT in 100% and 85.7% and after E-LLCOT in 42.9% and 71.4%, respectively. The posterior articular surface was not affected in any cadaver. CONCLUSION:: Anatomic structures can be damaged after both osteotomies. With the Hintermann osteotomy, the calcaneal anterior and medial articular surface can be protected to a larger extent than with the Evans osteotomy. CLINICAL RELEVANCE:: The Hintermann osteotomy seems to be superior, regarding damage of the articular surfaces of the subtalar joint. These findings have to be correlated with biomechanical and clinical studies before a final recommendation can be given, which osteotomy is superior.

Cartilage Surgery in Overweight Patients: Clinical and MRI Results after the Autologous Matrix-Induced Chondrogenesis Procedure.

Modern orthopaedic surgery provides a variety of techniques for cartilage repair. The Autologous Matrix-Induced Chondrogenesis (AMIC) procedure is a single-step technique with a collagen I/III scaffold for the treatment of full-thickness cartilage lesions. The aim of the study was to analyze the outcome of the AMIC procedure in overweight patients with knee cartilage defects. Overweight patients treated with AMIC surgery were followed up by clinical and MRI examination. 9 patients with a cartilage defect of the knee with a mean lesion size of 2.1 ± 1.2 cm2 and an average body mass index (BMI) of 29.3 were available for the follow-up. The Lysholm Score was significantly improved by the AMIC procedure (38 to 67, p ≤ 0.008). The VAS Score was significantly lower after the procedure (9 to 3, p ≤ 0.018). In the postoperative MOCART Scale, the scaffold reached defect covering of 80%. However, 2 patients had to be revised due to persisting knee pain. The AMIC procedure enhances pain reduction and gain of knee function for cartilage defects of overweight patients. However, in cases of an increased BMI, the patient had to be informed that success rate is reduced despite good defect covering.

Bioabsorbable magnesium versus standard titanium compression screws for fixation of distal metatarsal osteotomies - 3 year results of a randomized clinical trial.

BACKGROUND: For the treatment of hallux valgus commonly distal metatarsal osteotomies are performed. Persistent problems due to the hardware and the necessity of hardware removal has led to the development of absorbable implants. To overcome the limitations of formerly used materials for biodegradable implants, recently magnesium has been introduced as a novel implant material. This is the first study showing mid-term clinical and radiological (MRI) data after using magnesium implants for fixation of distal metatarsal osteotomies. MATERIAL AND METHODS: 26 patients with symptomatic hallux valgus were included in the study. They were randomly selected to be treated with a magnesium or standard titanium screw for fixation of a modified distal metatarsal osteotomy. The patients had a standardized clinical follow up and MRI investigation 3 years' post-surgery. The clinical tests included the range of motion of the MTP 1, the AOFAS, FAAM and SF-36 scores. Further on the pain was evaluated on a VAS. RESULTS: Eight patients of the magnesium group and 6 of the titanium group had a full clinical and MRI follow up 3 years postoperatively. One patient was lost to follow-up. All other patients could be interviewed, but denied full study participation. There was a significant improvement for all tested clinical scores (AOFAS, SF-36, FAAM, Pain-NRS) from pre-to postoperative investigation, but no statistically relevant difference between the groups. Magnesium implants showed significantly less artifacts in the MRI, no implant related cysts were found and the implant was under degradation three years postoperatively. CONCLUSION: In this study, bioabsorbable magnesium implants showed comparable clinical results to titanium standard implants 3 years after distal modified metatarsal osteotomy and were more suitable for radiologic analysis. LEVEL OF EVIDENCE: 2.

[Treatment Options for Neurogenic Drop Foot: A Systematic Literature Research]. / Behandlungsoptionen beim neurogenen Lähmungsfuß ­ eine systematische Literaturrecherche.

Background Neurogenic drop foot may be caused by central or peripheral lesions of the nervous system. Depending on whether the first or second motor neuron is damaged, a flaccid or spastic drop foot develops. Spastic drop foot persists as a residual long-term complication after stroke in about 14 % of patients. Various conservative and surgical treatment options are available. Methods This article is based on a systematic literature review for medical evidence of functional electrical stimulation (FES) with the keywords "functional electrical stimulation AND drop foot" and "functional electrical stimulation AND gait AND stroke" in PubMed and Cochrane databases. Randomised controlled trials and cohort studies of the past 10 years were selected according to specific criteria. Additionally, four guidelines were included. Results Current guidelines provide little guidance for practical treatment and fail to give due consideration to new surgical procedures such as neural implants. In 18 randomised controlled trials on FES in stroke patients with drop foot, the FES-treated population showed either significant superiority or non-inferiority versus control. Two cohort studies confirmed significant improvements by FES. Conclusion The analysis demonstrates the importance of considering causes and severity of drop foot as well as patients' pre- and post-operative conditions for choosing treatment options. For active, high-demand patients, neural implants are valuable treatment options.

Does a foot-drop implant improve kinetic and kinematic parameters in the foot and ankle?

INTRODUCTION: Unlike the drop foot therapy with ortheses, the therapeutic effect of an implantable peroneus nerve stimulator (iPNS) is not well described. IPNS is a dynamic therapy option which is placed directly to the motoric part of the peroneal nerve and evokes a dorsiflexion of the paralysed foot. This retrospective study evaluates the kinematics and kinetics in drop foot patients who were treated with an iPNS. MATERIALS AND METHODS: 18 subjects (mean age 51.3 years) with a chronic stroke-related drop foot were treated with an implantable peroneal nerve stimulator. After a mean follow-up from 12.5 months, kinematics and kinetics as well as spatiotemporal parameters were evaluated and compared in activated and deactivated iPNS. Therefore, a gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model was performed. RESULTS: The study showed significantly improved results in ankle dorsiflexion from 6.8° to 1.8° at the initial contact and from -7.3° to 0.9° during swing phase (p ≤ 0.004 and p ≤ 0.005, respectively). Likewise, we could measure improved kinetics, i.a. with a statistically significant improvement in vertical ground reaction force at loading response from 99.76 to 106.71 N/kg (p = 0.043). Enhanced spatiotemporal results in cadence, douple support, stride length, and walking speed could also be achieved, but without statistical significance (p > 0.05). CONCLUSIONS: The results show statistically significant improvement in ankle dorsiflexion and vertical ground reaction forces. These facts indicate a more gait stability and gait efficacy. Therefore, the use of an iPNS appears an encouraging therapeutic option for patients with a stroke-related drop foot.

Hip and knee effects after implantation of a drop foot stimulator.

BACKGROUND: An active ankle dorsiflexion is essential for a proper gait pattern. If there is a failure of the foot lifting, considerable impairments occur. The therapeutic effect of an implantable peroneus nerve stimulator (iPNS) for the ankle dorsiflexion is already approved by recent studies. However, possible affection for knee and hip motion after implantation of an iPNS is not well described. OBJECTIVE: The objective of this retrospective study was to examine with a patient cohort whether the use of iPNS induces a lower-extremity flexion withdrawal response in the form of an increased knee and hip flexion during swing phase. METHODS: Eighteen subjects (12 m/6 w) treated with an iPNS (ActiGait®, Otto Bock, Duderstadt, Germany) were examined in knee and hip motion by gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model after a mean follow up from 12.5 months. The data were evaluated and compared in activated and deactivated iPNS. RESULTS: Only little changes could be documented, as a slight average improvement in peak knee flexion during stand phase from 1.0° to 2.5° and peak hip flexion in stance from 3.1° to 2.1° In contrast, peak knee flexion during swing appeared similar (25.3° to 25.7°) same as peak hip flexion during swing. In comparison with the healthy extremity, a more symmetric course of the knee flexion during stand phase could be shown. CONCLUSIONS: No statistical significant improvements or changes in hip and knee joint could be shown in this study. Only a more symmetric knee flexion during stand phase and a less hip flexion during stand phase might be hints for a positive affection of iPNS for knee and hip joint. It seems that the positive effect of iPNS is only based on the improvement in ankle dorsiflexion according to the recent literature.

Early results using a biodegradable magnesium screw for modified chevron osteotomies.

This is the first larger study analyzing the use of magnesium-based screws for fixation of modified Chevron osteotomies in hallux valgus surgery. Forty-four patients (45 feet) were included in this prospective study. A modified Chevron osteotomy was performed on every patient and a magnesium screw used for fixation. The mean clinical follow up was 21.4 weeks. The mean age of the patients was 45.5 years. Forty patients could be provided with the implant, in four patients the surgeon decided to change to a standard metallic implant. The AOFAS, FAAM and pain NRS-scale improved markedly. The hallux valgus angle, intermetatarsal angle and sesamoid position improved significantly. Seven patients showed dorsal subluxation, rotation or medial shifting of the metatarsal heads within the first 3 months. One of these patients was revised, in all others the findings were considered clinically not significant or the patients refused revision. This study shows the feasibility of using magnesium screws in hallux valgus-surgery. Surgeons starting with the use of these implants should be aware of the proper handling of these implants and should know about corrosion effects during healing and its radiographic appearance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2207-2214, 2016.