Biomedical subjects

Beat Hintermann

Publications and source records attributed to Beat Hintermann.

7 recordsLinked to original sources

PubMed2003

Total ankle replacement.

Total ankle replacement is emerging as a viable treatment for symptomatic ankle arthritis that has not responded to nonoperative treatment. Most modern implant designs involve the use of a three-component, mobile-bearing implant. Although the results of the different design approaches are encouraging in limited clinical series, there is still the need for careful, long-term analyses to estimate to what extent the current designs are mimicking the biomechanics of the ankle joint. More attention must be paid to more accurate implantation techniques that result in a well-balanced ligament and allow the ligaments to act together with the replaced surfaces in a most physiologic manner. To improve the stability of the bone-implant interface over time, specific efforts should be made to better understand the extrinsic and intrinsic forces of the ankle joint, including the forces that are created by the prosthesis itself.

Ankle Joint↗

PubMed2003

Stress fractures of the medial great toe sesamoids in athletes.

The purpose of this study was to determine whether specific symptoms and findings are present in patients with symptomatic stress fractures of the sesamoids of the great toe and, if so, whether partial sesamoidectomy is sufficient for successful treatment. Five consecutive athletes (five females; mean age 16.8 years [range, 13 to 22 years]) with six feet that were treated for symptomatic stress fractures of the sesamoids of the great toe were included in this study. Four athletes (five feet) performed rhythmic sports gymnastics; the fifth athlete was a long jumper. Some swelling to the forefoot and activity-related pain that increased in forced dorsiflexion, but disappeared at rest was found in all patients. While plain X-rays evidenced fragmentation of the medial sesamoid, MRI (n=2) and frontal plane CT scan (n=3) did not always confirm the diagnosis, but bone scan (n=3) and axial as well as sagittal CT scan were useful to detect the pathology. After failure of conservative treatment measures, surgical excision of the proximal fragment was successful in all patients, and there were no complications. All patients were pain free and regained full sports activity within six months (range, 2.5 to six months). At final follow-up which averaged 50.6 months (range, 20 to 110 months), the overall clinical results were graded as good/excellent in all patients, and there was only one patient with of restriction sports activities. The obtained AOFAS-Hallux-Score was 95.3 (75 to 100) points. Apparently, stress fractures occur more often at the medial sesamoid, and females are mainly involved. When a stress fracture is suspected, bone scan and CT scan are suggested as more reliable in confirming the diagnosis than other imaging methods. When conservative treatment has failed, surgical excision of the proximal fragment is recommended.

Adolescent↗

PubMed2003

Accuracy of arthroscopic assessment of anterior ankle cartilage lesions.

PURPOSE: The accuracy of arthroscopic evaluation of the size of an osteochondral lesion in the ankle joint was assessed in 10 cadaver feet. MATERIALS AND METHODS: A rectangular osteochondral defect was created in the anterior part of the talus. A 5 mm 30 degrees arthroscope was utilized for evaluation of the size of the lesion from an anterior midline portal under carbon dioxide. RESULTS: The size of the defect averaged 77.2 +/- 31 mm2 (24-10(8) mm2). The difference between area of the defect and measurement of three independent investigators averaged 52%, 49% and 49%, respectively. CONCLUSION: The assessment of the size of an osteochondral lesion in the ankle joint based on arthroscopy implicates over- and underestimation of the defect.

Ankle Joint↗

PubMed2002

Posterior tibial tendon dysfunction and MR imaging in rheumatoid arthritis.

We present the case of a patient with long-standing rheumatoid arthritis and an acute onset of total dysfunction of the posterior tibial tendon. On MRI, a rupture of the tendon was apparent. Intraoperatively, however, massive tenosynovitis with stricture of the tendon was identified as the cause of posterior tibial tendon dysfunction. This case illustrates a pitfall in MRI imaging with potential diagnostic and therapeutic consequences.

Arthralgia↗

PubMed2002

Anatomical study of the medial ankle ligament complex.

The purpose of this in vitro study was to determine insertion area, length and thickness of the various bundles and their anatomical relationship with inter-individual differences. Twelve ankles from human cadavers (ages 56 to 95 years, from nine men and three women) were dissected to the capsuloligamentous structures. Marked inter-individual differences were found for the five main ligaments (tibiospring, tibiocalcaneal, posterior and anterior deep tibiotalar and superficial posterior tibiotalar). The tibionavicular ligament is a thickened fibrous layer of the ankle capsule. The tibiocalcaneal and tibiospring ligaments are the longest, and the tibiocalcaneal and posterior deep tibiotalar ligaments are the thickest of these ligaments. Fibrils run in the direction of the tibia or dorsally. Knowledge of the deltoid ligament complex is necessary for anatomically and biomechanically correct reconstruction that provides stability without hazard to biomechanics of function.

Aged↗

PubMed2002

Influence of screw type on obtained contact area and contact force in a cadaveric subtalar arthrodesis model.

The purpose of this study was to compare the compression effect of the 7.0-AO screw and the 6.5 mm Ideal Compression Screw (I.CO.S.) screw in an in vitro subtalar arthodesis model. Six fresh-frozen, human cadaver foot specimens were obtained for analysis. The subtalar joint was opened laterally without affecting the articular surfaces. ATekscan 5051 sensor with a maximum pressure of 250 PSI and a sensel-density of 62 sensel/sq-cm was placed into the joint, which allowed for continuous measurement of the contact area and contact forces achieved by one 7.0 AO-screw, and thereafter by one 6.5 I.CO.S.-screw. When tightening the screw, mean contact area increased by 0.21 cm2 for the AO-screw (p<0.05), and by 0.27 cm2 for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact area increased from 1.40 cm2 to 1.97 cm2 (p<0.05). The mean contact force also increased when tightening the screws. This increase was 7.6 N for the AO-screw (p<0.05) and 14.8 N for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact force increased from 54.9 N to 81.7 N (p<0.05). The obtained results have shown that the design of the screw influences the achieved compression force. The superior compression of the I.CO.S.-screw might be explained by the better gripping and additional compression mechanism of its head. The shape of the head of the cannulated AO-screw, in contrast, may be critical to resist against the weak cortical bone of the calcaneus, i.e. it can sink into soft bone resulting in a loss of compression force.

Aged↗

PubMedDate not supplied

Arthroscopic findings in patients with chronic ankle instability.

BACKGROUND: There are little objective data on structural changes of the chronically unstable ankle. Such knowledge could help with preoperative planning. HYPOTHESIS: Preoperative ankle arthroscopy provides important insights into the causes and mechanisms of ankle instability and the resulting disability. STUDY DESIGN: Case series. METHODS: From 1993 to 1999, arthroscopic examination was performed in the ankles of 148 patients with symptomatic chronic ankle instability that had lasted 6 months or more. All structural changes were recorded and compared with the clinical diagnosis. RESULTS: A rupture or elongation of the anterior talofibular ligament was noted in 86% of ankles, of the calcaneofibular ligament in 64%, and of the deltoid ligament in 40%. Cartilage damage was noted in 66% of ankles with lateral ligament injuries, whereas 98% of the ankles with deltoid ligament injuries had cartilage damage. Although lateral instability could be verified arthroscopically in 127 patients, medial instability was presumed clinically in 38 patients but was actually detected in 54 patients arthroscopically. CONCLUSION: Preoperative ankle arthroscopy revealed an essential amount of information that would otherwise have been undetected. For instance, the ligaments showed typical abnormalities corresponding to different entities of ankle instability and different intraarticular pathologic conditions.

Adolescent↗