Varus ankle osteoarthritis (OA) is typically associated with peritalar instability, which may result in altered subtalar joint position. This study aimed to determine the extent to which total ankle replacement (TAR) in varus ankle OA can restore the subtalar position alignment using 3-dimensional semi-automated measurements on WBCT. Fourteen patients (15 ankles, mean age 61) who underwent TAR for varus ankle OA were retrospectively analyzed using semi- automated measurements of the hindfoot based on pre-and postoperative weightbearing WBCT (WBCT) imaging. Eight 3-dimensional angular measurements were obtained to quantify the ankle and subtalar joint alignment. Twenty healthy individuals were served as a control groups and were used for reliability assessments. All ankle and hindfoot angles improved between preoperative and a minimum of 1 year (mean 2.1 years) postoperative and were statistically significant in 6 out of 8 angles (P<0.05). Values The post-op angles were in a similar range to as those of healthy controls were achieved in all measurements and did not demonstrated statistical difference (P>0.05). Our findings indicate that talus repositioning after TAR within the ankle mortise improves restores the subtalar position joint alignment within normal values. These data inform foot and ankle surgeons on the amount of correction at the level of the subtalar joint that can be expected after TAR. This may contribute to improved biomechanics of the hindfoot complex. However, future studies are required to implement these findings in surgical algorithms for TAR in prescence of hindfoot deformity.

Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present, studies lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee.

A systematic literature search was conducted on multiple databases combining “knee osteotomy” and “hindfoot/ankle alignment” search terms. Articles were screened and included according to the PRISMA guidelines. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales.

Three cadaveric, fourteen retrospective cohort and two case-control studies were eligible for review. Biomechanical hindfoot characteristics were positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment at the level of the hindfoot did also improve after knee osteotomy (n=13), except in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation or in case of a large HKA correction (>14.5°). Additionally, a pre-existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46–69%) and mean MINORS score was 9.2 out of 16 (range 6–12) for non-comparative and 16.5 out of 24 (range 15–18) for comparative studies.

Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset – or deterioration of hindfoot symptoms following knee osteotomy. Further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy.

Remark: Aline Van Oevelen and Arne Burssens contributed equally to this work

Introduction: Recent studies suggest that preservation of the calcaneocuboidal joint and a single medial approach may lead to equally good results as a conventional triple arthrodesis for painful malalignment or arthritis of the hindfoot. The theoretical advantage of a single medial approach for subtalar and talonavicular fusion is a lower risk for postoperative wound healing problems. The aim of our study was to assess the capability of the modified triple arthrodesis to correct hindfoot malalignment.

Methods: We retrospectively measured radiological parameters in 36 consecutive feet in 34 patients who underwent a modified triple arthrodesis. All operations were done with a single medial incision using rigid internal fixation with screws. Radiological evaluation was done at a mean of 15 months (range 6 to 34) postoperatively.

Results: The following angles showed a significant (p< 0.001) improvement: the talonavicular coverage from 23° (range,−51 to 51°) to 10° (range, −13 to 32°), the dorsoplantar talar-first metatarsal angle from 18° (range, −19 to 76°) to 9° (range, −11 to 28°), the lateral talo-calcaneal angle from 38° (range, 14 to 57°) to 28° (range, 12 to 44°), and the lateral talar-first metatarsal angle from −15° (range, −51 to 23°) to −4°(range, −18 to 22°). We encountered neither primary wound healing problems, nor bony nonunion.

Conclusions: In our study all radiological parameters improved postoperatively. We therefore believe that this is a safe and effective technique in the management of hindfoot deformity with predictable outcome even in patients with severe malalignment.

Background: While several studies in the last years tried to identify clinical limitations of patients suffering from end-stage ankle osteoarthritis (OA), very few attempted to assess foot and ankle function in a more objective biomechanical way, especially using dynamic pedobarography. The aim of the study was therefore to explore plantar pressure distribution characteristics in a large cohort of posttraumatic end-stage ankle OA.

Method: 120 patients (female, 54; male, 66; 120 cases) suffering from posttraumatic end-stage ankle OA were included. The clinical examination consisted of assessment of the AOFAS hindfoot score, a pain score, the range of motion (ROM) for ankle dorsiflexion and plantar flexion, and the body mass index (BMI, kg/m2). Radiological parameters included the radiological tibiotalar alignment and the radiological ankle OA grading. Plantar pressure distribution parameters were assessed using dynamic pedobarography.

Results: Intra-individual comparison between the affected and the opposite, asymptomatic ankle revealed significant differences for several parameters: maximum pressure force and contact area were decreased in the whole OA foot, such was maximum peak pressure in the hindfoot and toes area. No correlations could be found between clinical parameters, such as AOFAS hindfoot score, VAS for pain, and ROM, and the pedobarographic data. However, there was a positive correlation between dorsiflexion and the pedobarographic parameters for the hindfoot area.

Conclusion: In conclusion, posttraumatic end-stage ankle OA leads to significant alterations in plantar pressure distribution. These might be interpreted as an attempt of the patient to reduce the load on the painful ankle. Other explanations might be bony deformity and ankle malalignment as a consequence of either the initial trauma or of the degenerative process itself, pain related disuse atrophy of surrounding muscles, and scarred soft tissue.

Background: The diagnosis of implant-associated infections is difficult due to organisms attached to surfaces as biofilms. We hypothesize that diagnosis can be improved by removing biofilm microorganisms from implant surface by sonication, followed by Gram stain, culture and calorimetric detection in sonication fluid.

Methods: We prospectively included adult patients from May 2005 until December 2006 from whom an orthopedic implant (joint prosthesis or internal fixation device) was removed for any reason. Removed implants were vortexed and sonicated in solid containers 5 min at 40 kHz in 100 to 400 ml Ringer’s solution. The resulting sonicate was plated and incubated on aerobic and anaerobic blood agar and aliquots were in parallel incubated at 37°C for 3 days in an isothermal calorimeter TAM III (TA Instruments, New Castle, DE). Gram stain was performed on sonicates centrifuged at 5000 g for 10 min. Definitive infection diagnosis was of the implant was defined if purulence surrounding the implant, or growth of the same microorganism in ≥2 synovial fluid or intraoperative tissue specimens, or acute inflammation in histopathology, or a sinus tract was present. Sonicate culture was defined positive if > 10 cfu (colony forming units) grew/ml sonicate. Calorimetry was defined positive if heat flow rate increased ≥10 μW above baseline (detection limit ~0.3 μW).

Results: 846 implants (367 joint prostheses and 479 internal fixation devices) were studied, of which 171 (20%) were infected and 675 (80%) were aseptic cases. The sensitivity of intraoperative tissue cultures was 74%, of sonicate culture 89%, of sonicate Gram stain 51%, of sonicate calorimetry 96%. The specificity of all specimens was ≥95%.

Conclusion: Sonicate culture and calorimetry were more sensitive than intraoperative tissue cultures for diagnosing implant infections. With Gram stain of centrifuged sonicate, infection was diagnosed in > 50% cases. Sonicate culture and calorimetry may replace the current approach using multiple intraoperative periprosthetic tissue specimens, whenever the implant or part of it is removed.

Introduction: Ankle sprains are among the most common injuries in sports and recreational activities. 10 to 40% of the acute ankle sprains lead to chronic ankle instability (CAI), which can be divided into its mechanical and its functional division. The clinical-orthopaedic diagnosis of mechanical ankle instability (MAI) has been well established, whereas the etiology of the functional ankle instability (FAI) is still not objectively allocatable. The aim of this study was to identify neuromuscular patterns in lower leg muscles to objectively describe the FAI.

Methods: 15 patients suffering from unilateral CAI (mean age, 35.5 years) since 2.4 years (1–9 years) were examined. The patients were evaluated etiologically and clinically (VAS pain score, AOFAS Ankle Score, calf circumference, and SF-36). Electromyographic (EMG) measurements of surface EMG with determination of mean EMG frequency and intensity by wavelet transformation were taken synchronously with dynamic stabilometry measurements. Four lower leg muscles were detected: tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SO), and peroneus longus (PL) muscle. 15 healthy subjects were tested identically.

Results: Patients showed higher stability indices, higher VAS score, and lower AOFAS Ankle Score.

The mean EMG frequency was significantly lower for the PL (pathologic leg, 138.3 Hz; normal leg, 158.3 Hz, p< 0.001). Lower mean EMG intensity was found in the pathologic PL and GM. The mean EMG frequency of the TA was lower in the patient group, its intensity higher.

Discusssion and conclusion: Patients suffering CAI demonstrate weakened stability and impaired life quality. Neuromuscular patterns of the GM, PL and TA lead evidently to an objective etiology of the functional ankle instability. EMG patterns of four lower leg muscles indicate chronic changes in muscle morphology, such as degradation of type-II muscle fibres or modified velocity of motor unit action potentials. Accurate prevention and rehabilitation may compensate a MAI with a sufficient functional potential of lower leg muscles. This may also avoid operative treatment of MAI. The present study evidences the etiology of the FAI with objective parameters and indicates chronic changes in muscle morphology within CAI-Patients.

History and Background: The HINTEGRA^® Total Ankle Prosthesis was designed in 2000 by Dr. B. Hintermann (Basel, Switzerland); Dr. G. Dereymaeker (Pellenberg, Belgium); Dr. R. Viladot (Barcelona/Spain); and Dr. P. Diebold (Maxeville, France), and is manufactured by Newdeal SA in Lyon, France.

Design Features: The HINTEGRA^® Total Ankle Prosthesis is a non-constrained, three-component system that provides inversion/eversion stability. Axial rotation and normal flexion/extension mobility are provided by a mobile bearing element. Limits of motion are dependent on natural soft-tissue constraints: no mechanical prosthetic motion constraints are imposed for any ankle movement with this device. The HINTEGRA^® ankle uses all available bone surface for support. The anatomically shaped, flat tibial and talar components essentially resurface the tibia and talar dome, respectively, and wings hemiprosthetically replace degenerate medial and lateral facets (a potential source of pain and impingement). No more than 2 to 3 mm of bone removal on each side of the joint is necessary to insert the tibial and talar components. On the tibial side, most importantly, the bony architecture remains intact, and in particular, the anterior cortex is preserved. Perfect apposition with the hard subchondral bone is achieved by the flat resection of the bone and the flat surface of the component. Primary stability for coronal plane motion is provided by two screws inserted into the anterior shield, in the upper part of oval holes so that the settling process of the component is not hindered by axial loading. On the talar side, additional anterior support is provided by a shield, and pressfit is provided by the slightly curved wings. Two pegs facilitate the insertion of the talar component and provide additional stability, particularly against anterior-posterior translation. Another advantage of this concept is the instrumentation that allows reliable implantation of components.

Technique: The prosthesis is implanted through an anterior approach. In the case of malalignment, ligamentous instability, and concomitant osteoarthrosis of the distal joints, additional surgeries are considered before prosthetic implantation.

Complications: In the beginning, a major concern was the positioning of the talar component, which tended to slide too posteriorly while impacting and press fitting. With the addition of two talar pegs, the current design may resist such translational forces during press fitting.

There is evidence that positioning of the talar component too posteriorly may cause pain and limit dorsiflexion of the foot (probably because the posterior aspects of the deltoid ligament are over-tensioned), thereby the intrinsic forces are also increased which may cause unacceptable high shear forces at the bone-implant interface and/or component instability. In all but one of the seven revised talar components (out of the author’s first 400 cases), the component was positioned too posteriorly.

There is a potential risk for dislocation of the meniscal component either laterally or medially as long as no appropriate alignment and/or ligament balancing have been achieved during surgery. The author encountered this problem only in two of the first twenty cases; thereafter, no such complications occurred probably because of better understanding alignment and balancing the ankle.

A potential concern in uncemented resurfacing prostheses is the use of screws that may create stress shielding. The HINTEGRA^® ankle, however, uses oval holes on the tibial side so that some settling of the component during osteointegration is possible. As screw fixation is located eccentric to the load transfer area, the potential for stress shielding is in addition minimized.

Salvage of Complications: Special revision implants are available for salvage of failed components. On tibial side, components with a thicker plateau may serve to replace loosed bone stock and to get firm bony support more proximally, thereby preserving the original joint line (that means, the ankle ligaments are supposed to be properly used for stabilizing and guidance of the joint). On talar side, components with a flat undersurface allow flat resection of the talus, thus providing a wide area of bone support to the revision component.

Results: Between 05/2000 and 12/2006, 340 primary TAA were performed in 322 patients (females, 165; males, 157, age 57.3 ± 13.4 years). Underlying diagnosis was posttraumatic osteoarthritis in 272 ankles, primary osteoarthritis in 26 ankles and inflammatory arthritis in 42 ankles. All patients were clinically and radiologically assessed after 6.2 (1.1–7.5) years, and survivorship analysis was calculated. Revision of a metallic implant or conversion into ankle arthrodesis was taken as the endpoint.

The AOFAS Hindfoot Score improved from 42.1 (14–61) points preoperatively to 78.6 (44–100) points at follow-up. 205 ankles (60.5%) were completely pain free. The average range of motion was clinically 32.2° (range, 15° to 55°), and under fluoroscopy (that is, true ankle motion) 30.4° (range, 7° to 62°). Four ankles were revised to TAA (component loosening, 3; pain, 1), and 2 ankles (component loosening and recurrent misalignment, 1; pain, 1) were revised to ankle arthrodesis. Overall survivorship at 6 years was 98.2%, being 97.9% for the talar component and 98.8% for the tibial component.

Four ankles (1.2%) were successfully revised, and the obtained result at latest follow-up did not differ from those ankles without complications. Whereas, 2 ankles (0.6%) were revised to ankle arthrodesis.

In another series of 37 patients (37 ankles: STAR, 26 ankles; HINTEGRA, 3 ankles; AGILITY, 3 ankles, Büchel-Pappas, 2 ankles; MOBILITY, 2 ankles; SALTO, 1 ankle) with failed total ankle arthroplasty, revision arthroplasty was performed with the HINTEGRA^® ankle. All but one surgery were successful. At a mean follow-up of 3.6 (1.2–6.4) years, 29 patients (78.4%) were satisfied with the obtained result. The AOFAS Hindfoot Score improved from 39.2 (23–58) points pre-operatively to 72.8 (54–95) points. All but on implants were radiographically stable; in one case, the tibial component showed, at one year, still a radioluscency which may be considered as loosening. As the patient is completely pain free, no revision surgery was done.

In another series of 29 patients (30 ankles), a painful ankle fusion was taken down and ankle arthroplasty was performed with the HINTEGRA^® ankle. All surgeries were successful. At a mean follow-up of 3.4 (2–7.6) years, 24 patients (80%) were satisfied with the obtained result. The AOFAS Hindfoot Score improved from 34.1 (18–47) points preoperatively to 69.4 (48–90) points. The obtained motion for dorsi-/plantar flexion was clinically 23.5° (10°–40°) [52.6% of contra lateral ankle), and radiographically (“true ankle motion”) 24.5°(8°–24°) [54.4% of contra lateral ankle].

The author’s overall experience: more than 750 replacements with the HINTEGRA^® ankle in the last 8 years. The learning curve was rather long as some adjustments had to be performed, and there was need of some time to understand “ligament balancing” in ankle replacement in more detail. However, since then, an extremely high satisfaction rate was obtained, and most patients are doing very well. The revision rate has also turned down to < 2% despite, with increased experience, more complex cases may have been considered for ankle replacement.

Conclusion: Obviously, TAA using a current anatomic design of 3-component prosthesis (HINTEGRA) have evolved to a safe procedure with reliable results at mid- to long-term. These encouraging results support our belief that TAA has become a viable alternative to ankle arthrodesis even for younger patients and more difficult conditions, as often the case in posttraumatic osteoarthritis.

Purpose: Ankle sprains are among the most common injuries in sports and recreational activities. 10 to 40% of the acute ankle sprains lead to chronic ankle instability (CAI), which can be divided into its mechanical and its functional division. The clinical-orthopaedic diagnosis of mechanical ankle instability (MAI) has been well established, whereas the etiology of the functional ankle instability (FAI) is still not objectively allocatable. The aim of this study was to identify neuromuscular patterns in lower leg muscles to objectively describe the FAI.

Method: 15 patients suffering from unilateral CAI (mean age, 35.5 years) since 2.4 years (1–9 years) were examined. The patients were evaluated etiologically and clinically (VAS pain score, AOFAS Ankle Score, calf circumference, and SF-36). Electromyographic (EMG) measurements of surface EMG with determination of mean EMG frequency and intensity by wavelet transformation were taken synchronously with dynamic stabilometry measurements. Four lower leg muscles were detected: tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SO), and peroneus longus (PL) muscle. 15 healthy subjects were tested identically.

Results: Patients showed higher stability indices, higher VAS score, and lower AOFAS Ankle Score. The mean EMG frequency was significantly lower for the PL (pathologic leg, 138.3 Hz; normal leg, 158.3 Hz, p< 0.001). Lower mean EMG intensity was found in the pathologic PL and GM. The mean EMG frequency of the TA was lower in the patient group, its intensity higher.

Conclusion: Patients suffering CAI demonstrate weakened stability and impaired life quality. Neuromuscular patterns of the GM, PL and TA lead evidently to an objective etiology of the functional ankle instability. EMG patterns of four lower leg muscles indicate chronic changes in muscle morphology, such as degradation of type-II muscle fibres or modified velocity of motor unit action potentials. Accurate prevention and rehabilitation may compensate a MAI with a sufficient functional potential of lower leg muscles. This may also avoid operative treatment of MAI. The present study evidences the etiology of the FAI with objective parameters and indicates chronic changes in muscle morphology within CAI-Patients.

Introduction: Realigning the foot and good ligament balancing have been recognized to be the mainstay for successful reconstruction of complex hindfoot disorders and deformities. This is particularly true for posttraumatic conditions, where deformities and scarring might be the underlying cause of foot dysfunction. For surgical reconstruction, i.e. osteotomies, arthrodeses and total ankle replacement, references are needed for restoration of the anatomy and the function. Most surprisingly to date no data is available regarding dimensions on standard X-rays of the hindfoot. The purpose of this prospective study therefore was 1) to define relevant and reproducible measures on lateral hindfoot X-rays and 2) to assess their reliability.

Methods: 100 lateral view X-rays were taken. Dimensions assessed were the talar area covered by the tibia, the angle of the distal tibial joint plane to the tibial axis (tilt), the width of the tibia on the joint level, the height of the talus, the joint radius of the ankle joint and the offset of the centre of rotation from the tibial axis.

Results: The tibial coverage of the talus was 88.1 degrees (SD = 0.36), the angle of the distal tibial joint plane to the tibial axis (tilt) was 83 degrees (SD 3.6), the width of the distal tibia 33.6 mm (SD = 2.4), the radius of the ankle joint 18.6 mm (SD = 4.0) with an anterior offset of the centre of rotation of 1.7 mm and the height of the talus was 28.2 mm (SD = 2.1).

Conclusions: In case of symptomatic deformity any reconstruction, i.e. correcting osteotomies, ligament reconstruction, arthrodeses or arthroplasty, should aim to correct the foot in a physiological way; respecting the original dimensions of the hindfoot to achieve maximal benefit. Anterior-posterior translation of the talus may be a source of pain, restriction of motion and a cause of degenerative joint disease because of eccentric joint loading. This is also true for the height of the talus, which may have a significant impact on the hindfoot physiology. To achieve good biomechanical function, the positioning of the talus in relation to the tibia needs to be planned carefully prior to surgery. Poor coverage of the talus by the tibia and too much tilt of the distal tibia lead to higher joint forces and may be the cause of instability. Surgical procedures may fail if this is not recognized preoperatively. Several easily accessible measures on X-rays were found to be reliable to describe the hind-foot, as only small variation was found on the evaluated X-rays. If reconstruction of the hindfoot is required, care should be taken to identify the physiological joint geometry.

Introduction: Posttraumatic osteoarthritis of the ankle joint usually occurs secondary to an intraarticular fracture of the weight bearing ankle joint. The question whether also recurrent ankle sprain and /or chronic instability alone can cause this entity, is, however, still a question to debate. The aim of this retrospective study was, therefore, to analyse the history and findings of a consecutive series of patients that were treated for post-traumatic end-stage osteoarthrosis of the ankle.

Methods: The complete database (including physical exam, standard radiographs, patient questionnaire and AOFAS hindfoot score) of all patients was analysed.

Results: Out of 268 patients (females, 135 patients; males, 133) 221 (82.5%) had had a fracture (Fx) and 47 (17.5%) suffered from chronic ankle instability with recurrent sprains (but did not have a fracture). The latter group could be subdivided into 29 (10.8%) patients with recurrent sprains (RS) and 10 (6.7%) patients with only a single sprain (SS). The mean (range) delay between primary trauma and surgical treatment for endstage osteoarthritis was 21.1 (1–58) months for Fx, 37.07 (1–61) months for RS and 22.5 (5–48) months for SS.

Conclusion: Obviously, not only fractures, but also severe sprains and /or chronic instability play an important role as a cause of end stage osteaorthrosis of the ankle joint. The obtained results suggest that a single severe sprain (dislocation) can cause similar articular damages to an intraarticular fracture, as the time to develop osteoarthrosis does not differ. This is in contrast to the current opinion that ankle sprain, in most instances, does not result in symptomatic articular degeneration.