Biomedical subjects

V Valderrabano

Publications and source records attributed to V Valderrabano.

7 recordsLinked to original sources

PubMed2006

[Anatomical and biomechanical aspects of total ankle replacement].

The success of total ankle replacement highly depends on how successfully the physiological kinematics are maintained or reconstructed. Normal kinematics of the ankle joint can be replicated by designing an implant that is as close as possible to the normal bony anatomy, aligning the ankle and balancing the ligaments. Mimicking normal kinematics and kinetics of a healthy ankle joint will consequently decrease damaging joint contact stress forces and stress forces on the surrounding soft tissue, which may cause wear, implant failure, and pain. This article summarizes the anatomical and biomechanical basics that are required in total ankle replacement.

Ankle Joint↗

PubMed2006

[Muscle biomechanics in total ankle replacement].

The purpose of this orthopaedic-biomechanical study was to evaluate the muscle function in total ankle replacement (TAR) patients 1 year after surgery. Ten patients underwent a combined clinical and muscle biomechanical assessment prior to implantation and at the 1-year follow-up. Pain score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, ankle range of motion (ROM), and calf circumference difference between the affected leg and contralateral healthy leg were assessed. Biomechanically, isometric maximal voluntary torque for ankle dorsiflexion and plantar flexion was measured simultaneously with surface electromyography of four lower leg muscles. At follow-up, a significant improvement of the pain score (from 6.7 to 0.8 points), AOFAS ankle score (from 35.6 to 92.3 points), and ROM could be shown. Not significantly, the mean calf circumference difference between legs decreased from 2.2 to 1.4 cm. However, a significant increase was seen in the mean dorsiflexion (from 17.0 to 25.8 Nm) and plantar flexion torque (15.7 to 24.6 Nm) of the TAR-treated ankle. The mean EMG frequency content of the affected lower leg at TAR follow-up was lower than in the muscles of the contralateral healthy side. In contrast, the mean EMG intensity at TAR follow-up in side-comparison was statistically the same for all muscles. Ankle OA patients have better muscle function with TAR than under the arthritic condition, but they do not reach the normal level of the contralateral healthy leg 1 year after surgery.

Adult↗

PubMed2006

[The HINTEGRA ankle: short- and mid-term results].

The HINTEGRA ankle was developed as an attempt to specifically address the needs of minimal bone resection, extended bone support, proper ligament balancing, and minimal contact stresses within and around the prosthesis. The purpose of this article was to present the design and rationale of this prosthesis, and to analyze the clinical and radiological short- to mid-term results particularly with respect to the revisions and learning curve. Of the 278 total ankle replacements (between 2000 and 2004) with the HINTEGRA ankle, 271 ankles [patients: 261, males: 133, females: 128, age: 58.4 years (range: 25-90 years)] were clinically and radiographically assessed after 36.1 months (range: 12-64 months). The preoperative diagnosis was post-traumatic osteoarthrosis in 206 cases (76.0%), systemic arthritis in 34 cases (12.5%), and a primary osteoarthrosis in 31 cases (11.5%). Beside 4 perioperative and 19 early postoperative complications, a late complication occurred in 40 cases (14.8%). Of these, 22 complications (8.2%) were not related to implants, and 18 complications (6.6%) were related to implants. In all, 39 cases (14.4%) were revised; of these, 5 cases (1.8%) were revised to ankle arthrodesis. All other 34 revision arthroplasties were successful and did not evidence any differences in the outcome to the non-revised ankles. The AOFAS hindfoot score improved from 40.3 (range: 14-61) to 85.0 (range: 44-100) points at last follow-up. Radiographically, the tibial component was stable in all remaining 266 ankles, and no tilting of the component occurred since surgery. The talar component was positioned too posteriorly in 12 ankles (4.4%). The concept of minimal bone resection and wide bony support was shown to be successful on the tibial and talar sides. Most complications occurred in the early cases of this series, and the learning curve was found to be short and steep. Despite the high amount of post-traumatic cases with limited soft tissue quality, the obtained function, pain relief, and patient satisfaction were promising and, compared with other devices, the results mostly were superior. This may support the belief that anatomically shaped surfaces, as is the case in the HINTEGRA ankle, may advance success in total ankle replacement.

Adult↗

PubMed2001

Distribution of transcellular calcium and sodium transport pathways along mouse distal nephron.

The organization of Na(+) and Ca(2+) transport pathways along the mouse distal nephron is incompletely known. We revealed by immunohistochemistry a set of Ca(2+) and Na(+) transport proteins along the mouse distal convolution. The thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC) characterized the distal convoluted tubule (DCT). The amiloride-sensitive epithelial Na(+) channel (ENaC) colocalized with NCC in late DCT (DCT2) and extended to the downstream connecting tubule (CNT) and collecting duct (CD). In early DCT (DCT1), the basolateral Ca(2+)-extruding proteins [Na(+)/Ca(2+) exchanger (NCX), plasma membrane Ca(2+)-ATPase (PCMA)] and the cytoplasmic Ca(2+)-binding protein calbindin D(28K) (CB) were found at very low levels, whereas the cytoplasmic Ca(2+)/Mg(2+)-binding protein parvalbumin was highly abundant. NCX, PMCA, and CB prevailed in DCT2 and CNT, where we located the apical epithelial Ca(2+) channel (ECaC1). Its subcellular localization changed from apical in DCT2 to exclusively cytoplasmic at the end of CNT. NCX and PMCA decreased in parallel with the fading of ECaC1 in the apical membrane. All three of them were undetectable in CD. These findings disclose DCT2 and CNT as major sites for transcellular Ca(2+) transport in the mouse distal nephron. Cellular colocalization of Ca(2+) and Na(+) transport pathways suggests their mutual interactions in transport regulation.

Animals↗

PubMed2001

[Total ankle joint replacement].

We evaluated the short- to mid-term results of an unconstrained total ankle prosthesis (S.T.A.R.) with uncemented fixation. Seventy-nine consecutive ankle replacements were performed in 76 patients between 1996 and 2000. The initial diagnosis was posttraumatic osteoarthrosis in 51 cases (64%), primary osteoarthrosis in 14 cases (18%), and systemic joint affection in 14 cases (18%). Although 29 revision operations were necessary, all implants became fix, and no implants have been removed. At the last follow-up control, 38 patients (62%) were very satisfied, 20 patients (33%) were satisfied, and 3 patients (5%) were satisfied with reservations. The obtained range of motion was 35 degrees (range, 15 to 55 degrees), with a maximal plantarflexion of 27 degrees (range, 15 to 45 degrees) and dorsiflexion of 8 degrees (-3 to 20 degrees). The AOFAS-Hindfoot-Score of the 61 patients scored 84 points (range, 51 to 100 points). After settling of the implants within 6 weeks, no migration was noted in any case, and all implants were considered to be stable. The favorable results were considered to be a result of the mechanical properties of the S.T.A.R. total ankle prosthesis that allow for unconstrained motion. The rate of revisions, however, was too high, and it was considered to be a result of the design of tibial and talar component, the tibial fixation and the poor instrumentation. Nevertheless, total ankle replacement was shown to be a viable alternative to ankle arthrodesis. A longer follow-up is, however, mandatory to evaluate the long-term prognosis.

Adult↗

PubMed1999

Lengthening of the lateral column and reconstruction of the medial soft tissue for treatment of acquired flatfoot deformity associated with insufficiency of the posterior tibial tendon.

We analyzed our results of surgery for acquired flatfoot deformity after dysfunction of the posterior tibial tendon. This included lengthening the proximal lateral column by calcaneal osteotomy and reconstructing the medial soft tissue. Nineteen patients (9 women and 10 men; average age, 52.9 years [range, 24-72 years]) were treated for stage II and stage II-III insufficiency of the posterior tibial tendon. The medial soft tissue surgery included 18 reconstructions of the tendon, 11 transfers of the flexor digitorum longus tendon, 13 repairs of the deltoid ligament, and 3 repairs of the spring ligament. At follow-up (mean, 23.4 months), all patients had satisfactory restoration of their medial longitudinal arch, reduction of abduction in the forefoot, and restored height in the arch. All patients were able to bear weight fully on the foot that underwent surgery, and all but one were satisfied with the result achieved. The clinical result was rated as excellent in 6, good in 11, and fair in 2 cases. In all but one case, no loss of achieved correction in the foot was found. In one case, the calcaneocuboid joint had to undergo arthrodesis after 5 months because of painful degenerative joint disease. In the pes planovalgus and abductus deformities occurring in stage II disease, calcaneal osteotomy and reconstruction of the medial tendon and ligament seem to play a significant role in operative management. This was the case only when degenerative joint disease and significant subluxation of the subtalar or talonavicular joint or both had not already occurred. They seem to function by restoring more normal biomechanics, which allows reconstructed or transferred tendon to function successfully.

Adult↗

PubMed1999

[Lateral column lengthening by calcaneal osteotomy combined with soft tissue reconstruction for treatment of severe posterior tibial tendon dysfunction. Methods and preliminary results].

The purpose of this paper is to present principle and technique of proximal lateral column lengthening by calcaneal osteotomy and to critically analyze our preliminary results. 16 patients (7 female, 9 male; average age 52.3 years [24-72 years]) were treated for stage II to III posterior tibial tendon insufficiency by calcaneal osteotomy and medial soft tissue reconstruction (tendon reconstruction, 15; tendon transfer, 8; deltoid ligament repair, 10). When the AOFAS Ankle-Hindfoot Rating Scale was applied, these patients were shown to have significantly increased their scores from an average preoperative value of 49.1 to a mean postoperative value of 91.1 after a mean follow-up of 24.6 months. In all but one case no loss of achieved foot correction was noted. In one case, a fusion of the calcaneocuboid joint had to be performed after 5 months due to painful degenerative joint disease. At follow-up, all patients had satisfactory restoration of their medial longitudinal arch, reduction of forefoot abduction, and restored arch height. All patients were able to fully weight-bear the operated foot, and all patients were satisfied with the achieved result. In the pes planovalgus deformity occurring in stage II to III (as significant degenerative joint disease has not already occurred), osteotomies appear to have a significant role in the operative management and to function by restoring more normal biomechanics, thus allowing tendon reconstruction and tendon transfers to return to successful function.

Adult↗