Ankle - Clinical Data

Abstracts

Effect of implantation accuracy on ankle contact mechanics with a metallic focal resurfacing implant.

Anderson DD, Tochigi Y, Rudert MJ, Vaseenon T, Brown TD, Amendola A.
Department of Orthopaedics and Rehabilitation, The University of Iowa, Iowa City, IA 52242-1100, USA. don-anderson@uiowa.edu
J Bone Joint Surg Am. 2010 Jun;92(6):1490-500.
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Talar osteochondral defects can lead to joint degeneration. Focal resurfacing with a metallic implant has shown promise in other joints. We studied the effect of implantation accuracy on ankle contact mechanics after focal resurfacing of a defect in the talar dome. Static loading of seven cadaver ankles was performed before and after creation of a 15-mm-diameter osteochondral defect on the talar dome, and joint contact stresses were measured. The defect was then resurfaced with a metallic implant, with use of a custom implant-bone interface fixture that allowed fine control (in 0.25-mm steps) of implantation height. Stress measurements were repeated at heights of -0.5 to +0.5 mm relative to an as-implanted reference. Finite element analysis was used to determine the effect of implant height, post axis rotation, and valgus/varus tilt over a motion duty cycle. With the untreated defect, there was a 20% reduction in contact area and a 40% increase in peak contact stress, as well as a shift in the location of the most highly loaded region, as compared with the values in the intact condition. Resurfacing led to recovery of 90% of the contact area that had been measured in the intact specimen, but the peak contact stresses remained elevated. With the implant 0.25 mm proud, peak contact stress was 220% of that in the intact specimen. The results of the finite element analyses agreed closely with those of the experiments and additionally showed substantial variations in defect influences on contact stresses across the motion arc. Talar internal/external rotations also differed for the unfilled defect. Focal implant resurfacing substantially restored kinematics but did not restore the stresses to the levels in the intact specimens. Focal resurfacing with a metallic implant appears to have the potential to restore normal joint mechanics in ankles with a large talar osteochondral defect. However, contact stresses were found to be highly sensitive to implant positioning.

Novel metallic implantation technique for osteochondral defects of the medial talar dome. A cadaver study.

van Bergen CJ, Zengerink M, Blankevoort L, van Sterkenburg MN, van Oldenrijk J, van Dijk CN.
Orthopedic Research Center Amsterdam, Department of Orthopedic Surgery, Academic Medical Center, University of Amsterdam, The Netherlands. c.j.vanbergen@amc.nl
Acta Orthop. 2010 Aug;81(4):495-502.
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A metallic inlay implant (HemiCAP) with 15 offset sizes has been developed for the treatment of localized osteochondral defects of the medial talar dome. The aim of this study was to test the following hypotheses: (1) a matching offset size is available for each talus, (2) the prosthetic device can be reproducibly implanted slightly recessed in relation to the talar cartilage level, and (3) with this implantation level, excessive contact pressures on the opposite tibial cartilage are avoided. The prosthetic device was implanted in 11 intact fresh-frozen human cadaver ankles, aiming its surface 0.5 mm below cartilage level. The implantation level was measured at 4 margins of each implant. Intraarticular contact pressures were measured before and after implantation, with compressive forces of 1,000-2,000 N and the ankle joint in plantigrade position, 10 dorsiflexion, and 14 plantar flexion. There was a matching offset size available for each specimen. The mean implantation level was 0.45 (SD 0.18) mm below the cartilage surface. The defect area accounted for a median of 3% (0.02-18) of the total ankle contact pressure before implantation. This was reduced to 0.1% (0.02-13) after prosthetic implantation. These results suggest that the implant can be applied clinically in a safe way, with appropriate offset sizes for various talar domes and without excessive pressure on the opposite cartilage.

Difetti osteocondrali dell’astragalo: trattamento chirurgico e riabilitazione
Osteochondral defects of the talus: surgical treatment and rehabilitation

B. van Ooij, L. Kaas, M. L. Reilingh and C. N. van Dijk

ARCHIVIO DI ORTOPEDIA E REUMATOLOGIA
Volume 121, Number 4, 17-18, DOI: 10.1007/s10261-010-0052-5
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Un difetto osteocondrale sintomatico dell’astragalo è una lesione a carico della cartilagine talare e dell’osso subcondrale, causa di dolore profondo a carico dell’articolazione tibio-tarsica e/o di limitazione dell’articolarità, rigidità, sensazione di blocco e gonfiore. La visualizzazione di questo tipo di lesione non è sempre possibile utilizzando la radiologia tradizionale, ma sono spesso necessari per riconoscerla esami di secondo livello come TAC o RMN. Il trattamento iniziale è conservativo. Le possibilità di trattamento chirurgico includono il “debridement” (artroscopico), il “curettage”, la stimolazione midollare, la fissazione del frammento, trapianti ossei, autotrapianti cartilaginei, impianto di condrociti autologhi o HemiCAP. Questo articolo di revisione fornisce una visione d’insieme delle attuali tecniche chirurgiche nel trattamento delle lesioni osteocondrali dell’astragalo, con particolare attenzione alla riabilitazione post-operatoria.

Novel metal implantation technique for secondary osteochondral defects of the talus: preliminary results

van Bergen C., Reilingh M., van Dijk N.
Academic Medical Center, Orthopaedic Surgery, Amsterdam,Netherlands
Knee Surg Sports Traumatol Arthrosc (2010) 18 (Suppl 1):S314-15

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Osteochondral ankle defects mainly occur in a young and active population. In 63% of cases the defect is located on the medial talar dome. Arthroscopic debridement and microfracture is considered the primary treatment of defects up to 15 mm. To treat patients with a secondary osteochondral defect of the medial talar dome, we were involved in the development of a novel 15-mm diameter metal implant (HemiCAP). The set of 15 offset sizes was designed to anatomically correspond with various talar dome curvatures. We initially performed a biomechanical cadaver study that provided sufficient rationale for clinical use, in terms of operative technique and intra-articular contact pressure. The present study was undertaken to evaluate the clinical effect of the metal implantation technique in secondary osteochondral lesions of the medial talar dome in a prospective study. Methods: We have treated 16 patients since October 2007 by implanting the prosthetic device through a medial malleolar osteotomy (Figure 1).Two patients were excluded from the study; one because of simultaneous bone grafting for a massive osteochondral defect, and one because of diabetes mellitus. Nine patients have less than one year follow-up at the time of writing and are therefore left out of this analysis. We report five patients with one year follow-up. All patients had had one or two earlier operations without success. On preoperative CT, the median lesion size was 17 x 10 (range, 15-19 x 7-13) mm. The patients were assessed preoperatively and at 3, 6 and 12 months postoperatively, using Numeric Rating Scales (NRS) pain, Foot Ankle Outcome Score (FAOS), American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, and radiographs of the affected ankles. Results: All patients recovered well from their surgery and remained nonweight bearing for six weeks. Preoperatively, the median NRS at rest was 3 (range, 0-7), compared to 0 (0-4) after 1 year follow-up. NRS at walking significantly improved from a preoperative median of 6 (5-8) to 1 (0-4) at final follow-up (p\0.05). Most subscales of the FAOS improved with each assessment (Figure 2). The median AOFAS improved from 71 (47- 75) before surgery to 88 (75-100) at 1 year follow-up (p\0.05). There were no clinical or radiographic complications. Conclusions: The metallic implantation technique seems to be a promising treatment for secondary osteochondral defects of the talus, but more patients and longer follow-up are necessary to draw any firm conclusions.

Tertiary osteochondral defect of the talus treated by a novel contoured metal implant.

van Bergen CJ, Reilingh ML, van Dijk CN.
Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Knee Surg Sports Traumatol Arthrosc. 2011 Jun;19(6):999-1003. Epub 2011 Mar 16.
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The primary treatment of most osteochondral defects of the talus is arthroscopic debridement and bone marrow stimulation. There is no optimal treatment for large lesions or for those in which primary treatment has failed. We report a 20-year-old female patient with persistent symptoms after two previous arthroscopic procedures. Computed tomography showed a cystic defect of the medial talar dome, sized 17×8×8 mm. The patient was treated with a novel contoured metal implant. At 1 and 2 years after surgery, the patient reported considerable reduction in pain and had resumed playing korfball at competitive level.

Secondary Treatment of Osteochondral Defects of the Talus.

Clinical Monograph, Arthrosurface 2011
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