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.

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.

Biomechanical evaluation of naviculocuneiform fixation with lag screw and locking plates.

BACKGROUND: There have been no biomechanical evaluations of naviculocuneiform (NC) joint fixation. This study compared biomechanically 3 different fixation constructs for NC-1-3 joint fixation. METHODS: The present study compared the three fixation constructs lag screw with locking plate for each NC joint, two crossed lag screws for each NC joint and a separate lag screw for each NC joint with bridging locking plates. NC-1-3 fixation was performed stepwise, and rotation of each joint was evaluated after the application of each lag screw or locking plate and their removal. RESULTS: All examined fixation techniques led to a significant reduced rotation of the NC joints. For NC-1 rotation decreased from 2.8° (Range 1.2-6.6°) to 0.6° (0.2-3.0°) for lag screw and locking plate (p = 0.002) and from 5.0° (1.7-9.8°) to 1.0° (0.1-3.6°) for crossed lag screws (p = 0.002). For NC-2, locking plate constructs were better with 0.2° (0.1-0.5°) compared to crossed lag screw osteosynthesis with 0.9° (0.2-1.6°) (p = 0.011). CONCLUSION: Each evaluated fixation technique led to a reduced NC joint rotation. The fixation of any NC joint had no relevant effect on the adjacent NC joints. The results might support surgeons treating NC joint disorders.

Feasibility and reliability of DEXA analysis after total ankle arthroplasty: A cadaver study.

BACKGROUND: Although the outcomes of total ankle arthroplasty (TAA) have improved, unsolved problems such as stress shielding remain. Although dual energy X-ray absorptiometry (DEXA) is the "gold standard" for evaluation of these issues, it is rarely used in patients after TAA. This study aimed to establish a scan technique and to assess the mechanical changes in bone density caused by bone stock preparation. METHODS: Eight fresh-frozen cadaver legs were investigated by DEXA before TAA, with implant in situ, and after implant removal. Scan surface, bone mineral content, and bone mineral density were analysed to assess mechanical bone mass changes. RESULTS: We examined data for density changes by bone compression after TAA, and found "good" results for internal reliability but only "acceptable" results for external reliability. CONCLUSIONS: The results were reliable and reproducible. Using the present data, mechanical and biological processes can be considered together to understand the postoperative phases of bone remodelling after TAA.

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.

Treatment concepts for pes valgoplanus with concomitant changes of the ankle joint : Tibiotalocalcaneal arthrodesis, total ankle replacement and joint-preserving surgery.

Concomitant valgus deformities of the ankle joint are found in approximately 3% of patients with symptomatic flat foot deformities. Conservative treatment is mostly successful only in the short term or in low-demand patients. The operative treatment of flat foot deformities follows the standard algorithm for flat foot treatment. The ankle joint can be treated while retaining mobility or by arthrodesis depending on the degree and rigidity of the deformity, degenerative changes, patient factors and expectations. Achieving an orthograde hindfoot and midfoot is obligatory for successful treatment as well as in ankle reconstructive or arthrodesis procedures.

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.

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.

Stability of supramalleolar osteotomies using different implants in a sawbone model.

BACKGROUND: With ankle arthritis often affecting young patients, joint-sparing treatments instead of total joint replacement should be considered. Only a few implants were specially developed for supramalleolar osteotomies (SMOT). This study was performed to analyse the stability of different implants and their appropriateness for SMOT. METHODS: Twenty-five bone models (Sawbone Europe, Malmö, Sweden) were used for biomechanical testing. SMOT were performed as a uniplanar osteotomy, leaving 5 mm of lateral bone intact with a standardized gap of 8 mm. Five different plates commonly used for SMOT were assessed. For axial stability, the constructs were tested during 100 cycles for each load (150N and 800N) at a rate of 0.5 Hz. For rotational stability, each construct was subject to 100 cycles of 5 Nm torque at a rate of 0.25 Hz, performing three runs with an axial preload of 0N, 150N, or 800N. Ultimate axial load was performed for one-half and ultimate rotational load was performed for the other half of the constructs. In addition, the stiffness of the different constructs after failure was tested. RESULTS: All constructs showed high stability and could be tested until maximum cyclic load. There was no significant difference between the five plates, neither for stiffness (axial or rotational) nor for failure load (axial or rotational). One plate indicated superiority in axial failure testing without any significant difference. CONCLUSION: All implants could be tested until maximum load. The intact hinge apparently provides enough support to compensate for lower moment of inertia of some plates. LEVEL OF EVIDENCE: Not applicable.

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.

Results of HemiCAP® Implantation as a Salvage Procedure for Osteochondral Lesions of the Talus.

Osteochondral defects (OCDs) of the talus remain a surgical challenge, especially after failed primary treatment. The aim of the present study was to examine the clinical outcomes after HemiCAP® implantation for OCDs of the medial talar dome after failed previous surgery. Our retrospective study included 11 patients, who had undergone surgery from June 2009 to September 2012 for an OCD of the medial talar dome and received a HemiCAP® on the talus after failed previous surgery for OCD. The data were acquired using patients' medical records and standardized questionnaires, including the Foot and Ankle Outcome Score (FAOS), University of California at Los Angeles (UCLA) activity score, EQ-5D, numerical rating scale (NRS), and Short-Form 36-item Health Survey (SF-36). Using these scores, the possibility of returning to work and sports was determined. Any complications and the need for revision surgery were recorded. One patient refused to participate in the study, leaving 10 patients for evaluation. The mean age was 47.64 ± 10.97 years. The mean follow-up period was 43.5 ± 35.51 months. The FAOS and SF-36 subscale scores and the EQ-5D and UCLA activity scores did not improve significantly (p < .05). The mean postoperative pain score on the NRS improved significantly from 6.6 ± 1.77 preoperatively to 5.1 ± 2.02 postoperatively (p < .05). A greater body mass index led to worse postoperative outcomes with higher scores on the pain-NRS and less satisfaction (p < .05). Ten revisions for ongoing pain were performed in 7 patients (70.0%) within a mean of 28.4 ± 13.35 months of the initial procedure, and 6 patients (60%) indicated they would undergo surgery again. The results of the present study have shown that implantation of the HemiCAP® as a salvage procedure for OCDs of the talus is challenging and does not consistently lead to good clinical results. Also, overweight patients appear to have an increased risk of postoperative dissatisfaction and persistent ankle pain.

Biomechanical evaluation of different surgical techniques for treating patellar tendon ruptures.

PURPOSE: The aim of this study was to biomechanically assess patellar tendon repair techniques with additional cable wire or polydioxanone suture (PDS) cord augmentation in comparison with a suture-anchor repair technique. METHODS: Patellar tendon repair was performed in 60 specimens using a porcine bone model. Yield load, maximum load, stiffness and elongation of patellar tendon reconstructions with (1) cable wire augmentation, (2) PDS cord augmentation or (3) suture anchor repair were evaluated using a cyclic loading and load-to-failure test setup. RESULTS: In comparison with suture anchor repair, augmentation of the reconstruction with either cable wires or PDS cords provides significantly higher maximum loads (527 and 460 N vs. 301 N; p < 0.01 and p = 0,012, respectively) under load-to-failure testing and less elongation (8.81 mm ± 1.55 mm and 10.56 mm ± 3.1 mm vs. 18.38 mm ± 7.51 mm; p = 0.037 and p = 0.033, respectively) under cyclic loading conditions. CONCLUSION: Augmentation of a patellar tendon repair with either a cable wire or a PDS cord provides higher primary stability than suture anchor repair in patellar tendon ruptures. The study supports the use of additional augmentation of a tendon repair in the clinical setting in order to prevent loss of reduction and allow for early post-operative mobilisation.

Tibiocalcaneal arthrodesis as a limb salvage procedure for complex hindfoot deformities.

INTRODUCTION: Tibiocalcaneal (TC) arthrodesis is a limb salvage method for patients with severe deformities combined with necrosis and/or luxation of the talus. The aim of this study was to examine the clinical and radiological outcome of TC arthrodesis. MATERIALS AND METHODS: This retrospective study identified 12 patients with luxation and/or necrosis of the talus, due to charcot neuroarthropathy (83.3 %) or traumatic injuries (16.7 %). All patients underwent TC arthrodesis by an external fixator or nail arthrodesis. The mean follow up was 18 (6-36) months with a mean age of 51.3 (30-66) years. The data were collected using the AOFAS score as well as clinical and radiological examination during regular follow up. RESULTS: Seven (58.3 %) patients were treated with an external fixator, four (33.3 %) with nail arthrodesis and one (8.3 %) patient rejected both fixation methods. Four (100 %) patients achieved radiological and clinical bone union after nail arthrodesis and four (57.1 %) patients after external fixation. Three (42.9 %) patients treated by an external fixator showed a radiological moderate bone fusion, but a stable, asymptomatic non-union. One (8.3 %) case ended up in transfemoral amputation. Eleven patients (91.7 %) regained independent mobilization. The mean AOFAS score improved from 24.3 preoperatively to 66.7 postoperatively (p < 0.05). The postoperative satisfaction rate was good to excellent in 83.3 %. CONCLUSION: TC arthrodesis is a promising and effective method for the treatment of severe ankle deformities with talus luxation. It allows patient's return to mobility with good to excellent patient satisfaction.

Surgical Management of Charcot Deformity for the Foot and Ankle-Radiologic Outcome After Internal/External Fixation.

Charcot neuropathy (CN) is a severe joint disease that makes surgical planning very challenging, because it is combined with ankle instability, serious deformities, and recurrent ulceration. The aim of the present study was to examine the rate of bone fusion after external or internal fixation in patients with CN. We retrospectively examined 58 patients with CN who had undergone reconstruction of the ankle either with tibiotalocalcaneal or tibiocalcaneal arthrodesis. The mean age was 59.1 (range 26 to 81) years at surgery. Of the 58 patients, 38 were treated using intramedullary nail arthrodesis and 19 using an external fixator (1 patient received neither). At a mean follow-up period of 31.3 (range 12 to 57) months, limb salvage and bone fusion had been achieved in 94.83%. The mean time to bone fusion was 12 (range 6 to 18) months. Three patients (5.2%) required a more proximal amputation. All but these 3 patients gained independent mobilization in custom feet orthoses or off the shelf orthoses. Of the 58 patients in the present cohort, 56 (96.6%) would undergo surgery again. In conclusion, internal and external fixation both lead to promising results in the treatment of CN. Internal fixation should be preferred when no indications of ulcer or infection are present.

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.

Functional, Spiroergometric, and Subjective Comparisons Between Forearm Crutches and Hands-Free Single Crutches in a Crossover Study.

Background: Following below-knee surgery, the optimal medical mobility device remains controversial as adequate nonweightbearing of the operated extremity is critical to ensure successful healing. The use of forearm crutches (FACs) is well established but requires using both upper extremities. The hands-free single orthosis (HFSO) is an alternative that spares the upper extremities. This pilot study compared functional, spiroergometric, and subjective parameters between HFSO and FAC. Methods: Ten healthy (5 females, 5 males) participants were asked to use HFSOs and FACs in a randomized order. Five functional tests were performed: climbing stairs (CS), an L-shaped indoor course (IC), an outdoor course (OC), a 10-meter walk test (10MWT), and a 6-minute walk test (6MWT). Tripping events were counted while performing IC, OC, and 6MWT. Spiroergometric measurements consisted of a 2-step treadmill test with speeds of 1.5 and 2 km/h, each for 3 minutes. Lastly, a VAS questionnaire was completed to collect data regarding comfort, safety, pain, and recommendations. Results: Significant differences between both aids were observed in CS and IC (HFSO: 29.3 seconds; FAC: 26.1 seconds, P < .03; and HFSO: 33.2 seconds, FAC: 18 seconds, P < .001, respectively). The other functional tests showed no significant differences. The trip events were not significantly different between the use of the 2 aids. Spiroergometric tests showed significant differences regarding heart rate (HFSO: 131.1 bpm at 1.5 km/h and 131 bpm at 2 km/h; FAC: 148.1 bpm at 1.5 km/h and 161.8 bpm at 2 km/h) and oxygen consumption (HFSO: 15.4 mL/min/kg at 1.5 km/h and 16 mL/min/kg at 2 km/h; FAC: 18.3 mL/min/kg at 1.5 km/h and 21.9 mL/min/kg at 2 km/h) at both speeds (all P < .01). In addition, significantly different ratings regarding the items comfort, pain, and recommendation were recorded. Both aids were equally rated for safety. Conclusion: HFSOs may be an alternative to FACs, especially in activities that require physical stamina. Further prospective studies in patients with below-knee surgical intervention concerning everyday clinical use would be interesting. Level of Evidence: Level IV pilot-study.

Biomechanical Evaluation of Tarsometatarsal Fusion Comparing Crossing Lag Screws and Lag Screw With Locking Plate.

BACKGROUND: Tarsometatarsal (TMT) arthrodesis is a common operative procedure for end-stage arthritis of the TMT joints. To date, there is no consensus on the best fixation technique for TMT arthrodesis and which joints should be included. METHODS: Thirty fresh-frozen feet were divided into one group (15 feet) in which TMT joints I-III were fused with a lag screw and locking plate and a second group (15 feet) in which TMT joints I-III were fused with 2 crossing lag screws. The arthrodesis was performed stepwise with evaluation of mobility between the metatarsal and cuneiform bones after every application or removal of a lag screw or locking plate. RESULTS: Isolated lag-screw arthrodesis of the TMT I-III joints led to significantly increased stability in every joint (P < .05). Additional application of a locking plate caused further stability in every TMT joint (P < .05). An additional crossed lag screw did not significantly increase rigidity of the TMT II and III joints (P > .05). An IM screw did not influence the stability of the fused TMT joints. For TMT III arthrodesis, lag-screw and locking plate constructs were superior to crossed lag-screw fixation (P < .05). TMT I fusion does not support stability after TMT II and III arthrodesis. CONCLUSION: Each fixation technique provided sufficient stabilization of the TMT joints. Use of a lag screw plus locking plate might be superior to crossed screw fixation. An additional TMT I and/or III arthrodesis did not increase stability of an isolated TMT II arthrodesis. CLINICAL RELEVANCE: We report the first biomechanical evaluation of TMT I-III arthrodesis. Our results may help surgeons to choose among osteosynthesis techniques and which joints to include in performing arthrodesis of TMT I-III joints.

The Ankle Spacer-a hemiarthroplasty for treatment of severe osteochondral defects of the talus.

OBJECTIVE: The Ankle Spacer system has been developed as a joint-preserving option for patients with failed treatment of large talar osteochondral defects (OCDs). It is a one-piece implant system that replaces the articulating upper talus surface of the tibiotalar joint. INDICATIONS: Large OCDs with failed prior surgical intervention(s) and/or multiple talar OCDs on the talar surface, posttraumatic or degenerative osteoarthritis, or avascular necrosis of the talus. CONTRAINDICATIONS: Severe malalignment exceeding 7° and other ankle deformities that would not allow proper rasping of the talus, obesity, blood supply limitations, severe osteopenia, and previous or active infections. SURGICAL TECHNIQUE: The surgery is carried out via a central approach to the ankle joint. The tibiotalar joint was distracted to remove the cartilage on the upper talar surface with special talus rasps and to perform microfracture of the entire talar surface. The appropriate Ankle Spacer trial was then inserted into the joint and fluoroscopy was used to check for proper trial size and positioning. After thorough cleaning of the prepared bone bed, the Ankle Spacer was inserted with a special seating instrument. POSTOPERATIVE MANAGEMENT: One surgeon in our center implanted ten Ankle Spacers between April 2018 and October 2019. The first short-term data with follow-up of 3 months were collated. RESULTS: No implant-related complications were recorded. American Orthopaedic Foot and Ankle Society (AOFAS) score increased from 55.5 to 79.5 points, European Foot and Ankle Society (EFAS) score increased from 5.6 to 13.5 points, and pain score decreased from 3 to 1.1 points. None of the patients' radiographs showed signs of loosening or osteoarthritis progression.

Erratum: The computed tomography based anatomy of the ossa cuneiformia.

There is a lack of basic anatomic informations regarding the ossa cuneiformia. The aim of the present descriptive study was the detailed evaluation of the anatomy of the ossa cuneiformia. We analyzed 100 computer tomography scans of feet without deformities or previous trauma. The length, height and width of each cuneiforme and their articular surfaces were assessed. We itemized the data to gender differences and to foot length. The medial cuneiforme os had a length of 23.8±2.4 mm (mean ± standard deviation), a width of 15.9±2.7 mm and a height of 26.9±3.6 mm. The respective values for the intermediate cuneiforme were 17.7±1.9 mm, 12.4±3.1 mm and 20.8±2.9 mm and for the lateral cuneiforme 24.3±2.9 mm, 14.9±2.9 mm and 17.3±4.3 mm. We found statistical relevant differences regarding gender and foot length subgroups whereas not for all parameters. The present study illustrates basic anatomic data regarding the ossa cuneiformia. This information might be helpful for implant design and placement during midfoot surgery.