Franz Xaver Koeck

Evaluation of implant position and knee alignment after patient-specific unicompartmental knee arthroplasty

Implant positioning and knee alignment are two primary goals of successful unicompartmental knee arthroplasty. This prospective study outlines the radiographic results following 32 patient-specific unicompartmental medial resurfacing knee arthroplasties. By means of standardized pre- and postoperative radiographs of the knee in strictly AP and lateral view, AP weight bearing long leg images as well as preoperative CT-based planning drawings an analysis of implant positioning and leg axis correction was performed.The mean preoperative coronal femoro-tibial angle was corrected from 7° to 1° (p<0.001). The preoperative medial proximal tibial angle of 87° was corrected to 89° (p<0.001). The preoperative tibial slope of 5° could be maintained. The extent of the dorsal femoral cut was equivalent to the desired value of 5mm given by the CT-based planning guide. The mean accuracy of the tibial component fit was 0mm in antero-posterior and +1mm in medio-lateral projection. Patient-specific fixed bearing unicompartmental knee arthroplasty can restore leg axis reliably, obtain a medial proximal tibial angle of 90°, avoid an implant mal-positioning and ensure maximal tibial coverage.

Leg axis correction with ConforMIS iForma (interpositional device) in unicompartmental arthritis of the knee.

Degeneration of the meniscus and the articular cartilage in unicompartmental osteoarthritis of the knee results in progressive deformity of the leg axis. It is the aim of this study to evaluate if a leg axis correction can be achieved by implanting a customised metallic interpositional device for the knee (ConforMIS iForma™). Before and after implanting a ConforMIS iForma™ knee implant, a radiological analysis of the leg axis deviation in the frontal plane was performed prospectively in 27 patients by evaluating anteroposterior single-leg stance radiographs. We achieved a sufficient leg axis correction with an average correction of 3.8° and an averaged small under-adjustment of 0.9° by inserting the ConforMIS iForma™ interpositional knee implant. Apart from the primary treatment objective of articular surface restitution the ConforMIS iForma™ knee implant can be reliably used to correct axis deformity occurring with unicompartmental osteoarthritis of the knee.RésuméLa déformation progressive du membre inférieur entraîne lorsqu’existe une arthrose mono-compartimentale un dégénérescence du ménisque et du cartilage articulaire homolatéral. Le but de cette étude est d’évaluer la correction d’axe par un implant métallique d’interposition au niveau du genou(ConforMIS iForma™). avant et après implantation de l’implant ConforMIS iForma™ une analyse radiologique prospective de la déviation des membres dans le plan frontal a été réalisée, chez 27 patients avec radiographies de face et de profil. il est possible grâce à ce matériel d’avoir une correction moyenne de 3,8° avec une hypo correction de 0,9°. compte-tenu de l’objectif que nous nous étions fixés, l’utilisation de cet implant (ConforMIS iForma™) au niveau du genou, permet d’avoir une correction fiable de l’axe lorsque l’on traite des athroses mono-compartimentales.

Arterial anatomy of the hallucal sesamoids.

The aim of this study was to analyze the arterial supply of the sesamoid bones of the hallux. Twenty‐two feet from adult cadavers were injected with epoxide resin or an acrylic polymer in methyl methacrylate (Acrifix®) and subsequently processed by two slice plastination methods and the enzyme maceration technique. Afterwards, the arterial supply of the sesamoid bones was studied. The first plantar metatarsal artery provided a medial branch to the medial sesamoid bone. The main branch of the first plantar metatarsal artery continued its course distally along the lateral side of the lateral sesamoid and supplied it. The supplying arteries penetrated the sesamoid bones on the proximal, plantar, and distal sides. The analysis and cataloging of the microvascular anatomy of the sesamoids revealed the first plantar metatarsal artery as the main arterial source to the medial and lateral sesamoid bones. In addition, the first plantar metatarsal artery ran along the lateral plantar side of the lateral sesamoid bone, suggesting that this artery is at increased risk during soft‐tissue procedures such as hallux valgus surgery. Clin. Anat. 22:755–760, 2009.

Gait Analysis after Tibialis Anterior Tendon Rupture Repair Using Z-Plasty

Other than limited reports regarding surgical outcomes, little information is available regarding whether Z-plasty of the tibialis anterior results in normal gait kinematics. We included 5 patients with spontaneous ruptures in the present retrospective study. The mean interval between rupture and operative treatment was 2.6 ± 2.6 months (standard deviation). The mean age of the patients was 63 (range 40 to 80) years. All patients were treated operatively with Z-plasty. Gait analysis was used to study the outcome, comparing the operated and nonoperated limbs. The patients were tested after a mean follow-up of 22 (range 12 to 33) months. No repeat ruptures were noted. Plantarflexion was significantly diminished during the preswing phase and initial swing phase in the operated limbs compared with the uninjured limbs. Plantarflexion was significantly increased during the terminal swing phase on the operated side. Knee flexion was nearly symmetrical. No significant differences regarding the temporospatial parameters were noted. We recommend Z-plasty for ruptures of the tibialis anterior tendon as a safe and effective procedure. However, this technique does not fully restore a physiologic gait pattern.

Predominance of synovial sensory nerve fibers in arthrofibrosis following total knee arthroplasty compared to osteoarthritis of the knee.

BackgroundSo far, there exists no golden standard for the treatment of arthrofibrosis (AF) following total knee arthroplasty (TKA). Although pain is a hallmark of AF, nociceptive nerve fibers have never been investigated in affected joint tissue.MethodsA total of 24 patients with osteoarthritis (OA) of the knee (n = 12) and post-TKA AF of the knee (n = 12) were included. Along evaluation of typical clinical signs and symptoms by using the Knee Society Clinical Rating System (KSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC index), the innervation of joint tissue was studied by semiquantitative immunofluorescence of nerve fibers.ResultsPatients with AF compared to OA had a lower KSS and lower KOOS. In all compartments (anterior, medial, and lateral recesses), the density of synovial sympathetic nerve fibers was significantly higher in OA compared to AF, which was also true for the density of sensory nerve fibers in the medial and lateral recesses. In synovial tissue of the anterior recess of patients with AF compared to OA, the density of nociceptive sensory nerve fibers was significantly higher relative to sympathetic nerve fibers. This was similarly observed in the neighboring infrapatellar fat pad of the knee.ConclusionsSimilar as in many painful musculoskeletal diseases, this study indicates that patients with arthrofibrosis of the knee after TKA demonstrate a preponderance of profibrotic sensory nerve fibers over antifibrotic sympathetic nerve fibers. This could serve as a starting point for AF therapy with specific antifibrotic pain medication or regional anesthetic techniques.

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

IntroductionDiabetic 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.MethodsTwenty 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.ResultsThe 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/ConclusionA 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.

Removal and successful re-implantation of a customized interpositional knee device following an early postoperative infection: A case report

We report the first case of early postoperative infection after a medial hemiarthroplasty of the knee with a customized ConforMIS iForma™ interpositional device. The infection was treated successfully by revision surgery with implant removal and antibiotic therapy. Despite the additional diagnosis of rheumatoid arthritis that did not affect the treated knee, the preservation of bony and ligamentous structures enabled a successful re-implantation of another iForma™ implant 9 months later with good clinical results at follow-up examination 1 year postoperatively. This is very much in contrast to the extensive and complex revision surgery, with significant bone loss, in patients with infected unicompartmental or total knee arthroplasties. The iForma™ device may be an alternative treatment option in early and moderate unicompartmental arthritis of the knee, with easy revision with the same type of implant in the rare case of infection.

Postural Stability after Unicondylar Knee Arthroplasty and Patient-Specific Interpositional Knee Spacer

Purpose and Hypothesis. Knee osteoarthritis results, inter alia, in decreased postural stability. After arthroplasty, postural stability recovers, but it is unclear whether this can be ascribed to a reduction of pain or to the preserving of receptor-rich intraarticular soft tissue and natural knee kinematics. The objective of this study was to evaluate whether an unicondylar knee arthroplasty provides better results regarding postural stability or a patient-specific knee spacer. Methods. In this comparative study, we assessed functional results and postural stability 16 months after 20 unicondylar knee arthroplasties (group A) and 20 patient-specific interpositional knee device implantations (group B). Patients were evaluated using the KSS and WOMAC score. Postural stability was analysed during single leg stance on a force platform (Biodex Balance System). Results. Concerning postural stability, range of motion (ROM), and KSS 16 months after the procedure, there were no significant differences between both groups. Conclusion. Successful treatment of knee osteoarthritis restores postural stability to the level of the contralateral side, regardless of the implant device.