Biomedical subjects

Michael A Kuhn

Publications and source records attributed to Michael A Kuhn.

3 recordsLinked to original sources

PubMed2006

Revision lateral ankle reconstruction.

BACKGROUND: Symptomatic lateral ankle instability is a common source of disability in an active population. While most incidences are successfully treated by conservative measures, some individuals require lateral ankle reconstruction. A commonly performed procedure is the Gould modification of the Broström lateral ankle reconstruction. Despite its success, some individuals experience recurrent instability through reinjury. Revision surgery often involves nonanatomic reconstruction using tendon grafts that may restrict normal ankle and subtalar motion and can result in persistent postoperative pain and disability. The purpose of this study was to demonstrate an equivalent success rate using a more anatomic revision lateral ankle reconstruction based on the Gould modification of the Broström concept. METHODS: We retrospectively reviewed 15 consecutive patients who had a revision lateral ankle reconstruction between 1992 and 2000. All procedures were done by a single surgeon (FGL). Patients who exhibited hindfoot varus and dynamic heel rollout had a valgus calcaneal osteotomy. Patients were asked to complete a 100-point questionnaire postoperatively. RESULTS: All patients reported improvement in ankle function, decreased pain, and no episodes of instability compared to preoperative assessments. Excellent results were achieved in 12 of 15 patients which was consistent with published data from index Broström reconstructions. Four patients who had fixed hindfoot varus and dynamic ankle rollout had valgus calcaneal osteotomies. All patients returned to an active lifestyles including sports and military service. CONCLUSION: Our findings suggest that a revision anatomic lateral ankle reconstruction is an effective option. A thorough clinical evaluation was mandatory to assess hindfoot valgus with dynamic ankle rollout for which a valgus calcaneal osteotomy was included in the procedure. We believe that tendon sacrificing procedures can be avoided in most patients, but soft-tissue structures must be assessed intraoperatively and the surgical approach planned to allow for conversion if necessary.

Adolescent↗

PubMed2005

Blood flow to the metatarsal head after chevron bunionectomy.

BACKGROUND: Avascular necrosis (AVN) of the metatarsal head is a known, but infrequent, complication of a chevron bunionectomy. An increased incidence of AVN has been reported with the addition of an adductor tenotomy and lateral release. The purpose of this study was to document the vascular insult to the metatarsal head during a chevron bunionectomy with adductor tenotomy and lateral release through direct blood flow measurements during the procedure. METHODS: A prospective study of 20 patients was performed. A chevron bunionectomy was performed under regional anesthesia without tourniquet control by two surgeons. Blood flow recordings were documented during key portions of the procedure: baseline, medial capsulotomy, adductor tenotomy and lateral release, and chevron osteotomy. The Periflux PF3 laser Doppler probe (Perimed, Inc., North Royalton, OH) was used to record blood flow. Mauchly's test of Sphericity and a pairwise comparison were performed with significance defined as p < 0.05. All patients had radiographs 3 months postoperatively to assess AVN. RESULTS: There was a statistically significant decrease in blood flow to the metatarsal head at each portion of the procedure. The greatest insult occurred with the medial capsulotomy (45% decrease). The lateral release and adductor tenotomy caused a 13% decrease and the chevron osteotomy caused a 13% decrease, totaling 71% decrease from the baseline. There was no evidence of AVN at 3 months, and all patients had radiographic evidence of union without recurrence or over-correction. CONCLUSION: The addition of the adductor tenotomy with lateral release often is crucial to obtain the desired correction and avoid the complication of recurrence. The disruption of microvascular blood flow to the metatarsal head after a chevron bunionectomy with adductor tenotomy and lateral release was not complete, totaling 71% in the study population. The greatest insult occurred with the medial capsulotomy. There were no occurrences of AVN. Despite the fear of AVN, this study demonstrated that an adductor tenotomy and lateral release could be done safely completed with a chevron bunionectomy.

Adult↗

PubMed2003

Fate of polytetrafluoroethylene monocusp pulmonary valves in an animal model.

Creation of a competent pulmonary monocusp valve facilitates transition from pressure to volume overload following right ventricular outflow tract reconstruction. To determine intermediate-term results and performance of the different types of polytetrafluoroethylene membrane used to construct monocusp valves and transannular patches, 12 infant lambs underwent excision of the native pulmonary valve and insertion of a monocusp valve and transannular patch made from one of 4 types of membrane. Echocardiography was performed after 3, 6, 9, and 12 months, and cardiac catheterization was carried out prior to animal sacrifice at 6 (n = 4) or 12 (n = 8) months. There was no postoperative morbidity or mortality. On echocardiography, 6 valves were mobile (50%), 4 had diminished mobility (33%), and 2 were fixed (17%) prior to sacrifice. At catheterization, mild, moderate, and severe pulmonary regurgitation was observed in 4 valves each (33%), with no stenosis. Right ventricular outflow tract reconstruction with polytetrafluoroethylene monocusp valves can be safely accomplished with good early competence, variable degrees of late insufficiency, and no stenosis. Compared to an open microstructure, the closed polytetrafluoroethylene microstructure showed a milder fibroinflammatory reaction and fewer foci of microcalcification, with sparing of the free edge of the monocusp; this correlated with better intermediate-term hemodynamic performance.

Animals↗