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Biomedical subjects

B Hintermann

Publications and source records attributed to B Hintermann.

At least 37 records · Page 2Linked to original sources
PubMed1998

Pronation in runners. Implications for injuries.

In spite of some significant progress in the understanding of the biomechanics of the ankle joint complex, especially the coupling mechanism between foot and leg, various mechanisms causing overuse injuries in the lower extremities are still poorly understood. Some increased pronation of the foot is often physiological, but excessive pronation is potentially harmful. Compensatory overpronation may occur for anatomical reasons. However, not only the amount of foot eversion, but also the way this eversion is transferred into tibial rotation may be crucial to the overloading stress on the knee. In other words, the individual transfer mechanism of foot eversion into internal tibial rotation may be of some predictable value for lower extremity overloading and related injuries. Further research is necessary to improve the functional understanding of anatomical and biomechanical abnormalities and their pathological value in predicting overuse injuries.

Ankle Injuries↗
PubMed1998

[Biomechanics of the ankle joint--injury mechanisms].

The complex mechanics of the ankle joint complex depends highly on the integrity of the ankle ligaments. An incomplete restoration of the antero-fibular ligament after trauma may result in a mechanical dissociation of the talus from the ankle mortise. The force that is needed to induce a non-physiological movement of the foot is determined by the individual configuration of the bony and articular structures of the hindfoot. A pes cavus is less protected to suffer of an ankle sprain than a flatfoot. As the leverarm of the peroneal muscles decreases with increasing plantarflexion of the foot, the active protection to resist against a supination stress decreases with plantarflexion. These findings have significant implications for the practice. First of all an adequate treatment of any ankle sprain is necessary to restore the mechanical interplay of the ankle joint complex. Ankle orthoses should protect the foot against supination stress and excessive plantarflexion. The prevention of ankle injury may be significantly improved by recognition of the individual mechanical disposition.

Ankle Injuries↗
PubMed1997

[Primary management of comminuted humeral head fracture in the elderly patient with a humerus head prosthesis].

The purpose of this prospective study was to determine the early subjective and functional result and outcome after primary implantation of humeral endoprosthesis in severely comminuted humeral head fractures in elderly patients. From 1993 to 1995, 27 humeral head fractures (27 patients) were treated by primary implantation of a Neer II modular shoulder prosthesis. Of these, 23 patients were women, 4 patients were men. The average age of patients was 76 (48-91) years. Postoperatively, one shoulder had to be mobilized under general anesthesia. Of the 27 patients 21 could be clinically examined after 16 (3-29) months postoperatively; 4 patients had died in the meantime, 2 did not come to the control examination because of a great distance and because they were happy. The average Constant Score was 48 (25-76) points; the difference to the other shoulder was 30 (18-69) points. Of the 21 patients 19 were satisfied by the result and 20 would reaccept the same procedure. These preliminary results suggest that primary shoulder prosthesis in humeral head fractures in the elderly patient is a valuable alternative option.

Aged↗
PubMed1996

Arthroscopic assessment of the chronic unstable ankle joint.

The purpose of this study was to evaluate prospectively the findings during arthroscopy in patients with chronic instability of the ankle joint. One hundred and ten consecutive patients who had suffered at least two ankle sprains and were symptomatic for at least 6 months were included in this study. A complete rupture of the anterior talofibular ligament was found in 64%, of the calcaneofibular ligament in 41% and of the deltoid ligament in 6%. Cartilage lesions of the talus were seen in 54% of the joints, more of them medial (56%) than lateral (15%) or ventral (20%). Other frequently observed findings were synovialitis (38%), rupture of the syndesmosis (7%), and ventral scarring (6%). While cartilage damage was found independently of the lateral ligament injuries, all complete tears of the deltoid ligament were associated with cartilage injury of the talus. Medial instability was assessed in five ankles clinically and found arthroscopically in 23 ankle joints. Our arthroscopic findings show that chronic instability of the ankle joint is associated with various pathological conditions of ligaments, capsule and cartilage. It can therefore give essential information about the status of the chronic unstable joint with regard to the choice of operative or conservative treatment.

Adolescent↗
PubMed1996

[Biomechanics of the ligaments of the unstable ankle joint].

Ligament rupture occurs at the maximum breaking load. During ligament healing, contraction and remodeling of the scar is sufficiently advanced at 6 weeks to reach 60 to 70% of the initial strength. There is evidence of an early improvement in biomechanical properties of repaired ligaments. This advantage, however, may not be sustained as, after one year, sutured and unsutured ligaments have nearly equal length when measured at rest and comparable failure strength when subjected to exercise. Each of the ankle ligaments has a role in stabilizing the ankle and/or subtalar joint. Beside of maintaining lateral ankle stability, the lateral ankle ligaments have been shown to play a significant role in providing rotational ankle stability. This is especially true for the anterior talofibular ligament. A loss of this ligament does allow for an increase in foot inversion and external rotation of the leg to occur, without any tilting of the talus or subtalar gapping. It is this increase in foot inversion which may lead to a symptomatic instability. When treating ankle instability, it is therefore important for the clinician to take the alteration of hindfoot biomechanics into consideration. This is especially the case for any surgical repair of injured ankle ligaments. Unphysiological tenodesis procedures should be avoided.

Ankle Injuries↗
PubMed1996

[Diagnostic imaging of ankle joint instability].

The value of the available diagnostic methods for the evaluation of the unstable ankle joint still is under discussion. This is a result of the increasing knowledge of basic biomechanics. It has been demonstrated that ankle instability is not restricted to two planes, but can be multidirectional or rotatory. There is also a trend to conservative treatment of acute unstable ankle joints. This paper presents the actual diagnostic tools for evaluation of the unstable ankle joint with regard to their efficiency. Stress views, sonography, MRI and arthrography will be discussed.

Ankle Injuries↗
PubMed1996

[Arthroscopic findings in the unstable upper ankle joint].

The purpose of this prospective study was the assessment of the chronic unstable ankle joint. With regard to cartilage and ligament lesions this was done arthroscopically. 99 consecutive arthroscopies were performed in patients with symptomatic chronic ankle instability. There were 67 complete ruptures of the anterior talofibular ligament and 45 complete ruptures of the calcaneofibular ligament. A complete rupture of the deltoid ligament was found in 6 cases, always combined with lesions of the lateral ligaments. Cartilage damage of the talus was noted in 51 cases and of the tibial pilon in 12 cases. While all complete lesions of the deltoid ligament were associated with talar cartilage damage, this was different for lateral ligament lesions. 11/22 ruptures of the talofibular ligament were associated with cartilage damage of the talus and 11/22 ruptures presented with an intact talar cartilage. Combined ruptures of the talofibular and the calcaneofibular ligament were associated with talar cartilage damage in 21 cases and presented with intact cartilage in 24 cases. This study demonstrated a near equal distribution of intact and damaged articular cartilage in the presence of lateral ligament lesions indicating that the status of the ligaments allows no conclusion with regard to the cartilage. Arthroscopy therefore can give essential information about the status of the unstable ankle joint concerning operative or conservative treatment.

Adolescent↗
PubMed1996

[Effectiveness of outer stability aids on rotational stability of the ankle joints].

The main goal in nonoperative treatment of lateral ankle ligament injuries is the reduction of the possible supination at the ankle joint complex. Complete ligament healing can only be achieved when protected from overstress. There is general agreement that talar tilt should be avoided. Recent reports, however, have shown that instability of the ankle joint is at least in one form an axial rotational one. Therefore, the reduction of tibial rotation should also be taken into consideration. The purpose of this study was to determine the effect of three commonly used ankle braces and ankle taping on rotational stability of the ankle joint complex. The Künzli stabilizing shoe was the only orthosis that stabilized sufficiently the ankle joint complex when the foot was in slight plantarflexion. The reduction of external tibial rotation was in foot flexion of 20 degrees: Künzli stabilizing shoe, 58%; Aircast, 23%; Mikros, 12%; and taping, 10%. This becomes more relevant as this foot position is the most dangerous one where most of the ligament injuries does occur. It could be that the insufficient effect of various ankle braces on rotational stability may be the reason for residual problems after ankle sprain.

Adult↗
PubMed1996

[Dwyer osteotomy with or without lateral stabilization in calcaneus varus with lateral ligament insufficiency of the upper ankle joint].

Varus deformity is a well known problem in the treatment of chronic lateral ankle instability. Surgical correction is recommended occasionally. The goal of this study was to show the effect of a calcaneal Dwyer osteotomy in patients suffering from a functional instability. We examined 6 patients, who underwent 7 calcaneal osteotomies. Postoperatively all patients maintained stability. No recurrence of a supination trauma was observed.

Adult↗
PubMed1996

Influence of ankle ligaments on tibial rotation: an in vitro study.

The purpose of this study was to clarify the role of the ankle ligaments in controlling the tibial rotation for different foot positions. A 6 degrees of freedom device was constructed for in vitro simulation of this movement transfer during the support phase of gait. Tibia rotation angle was measured for different foot positions and vertical loads, while the ligament integrity was modified. Data were collected from eight legs of four different cadavers. The results showed that vertical loading is unimportant to influence tibial rotation, while the lateral ankle ligaments have significant influence, especially during eversion. It was concluded that chronic partial or total lateral ankle instability may contribute to knee and foot injuries through abnormal tibial rotation.

Aged↗
PubMed1996

The first metatarsal rise sign: a simple, sensitive sign of tibialis posterior tendon dysfunction.

Although foot deformation starts in the early stage of tibialis posterior (TP) tendon dysfunction, this condition is often overlooked or misdiagnosed. We observed consistently a clinical sign of TP tendon dysfunction that, to our knowledge, has not yet been described. Patients were tested while they were standing and fully weight-bearing with both feet. When the shank of the affected foot was taken with one hand and externally rotated, or when the heel of the affected foot was taken with one hand and brought passively into a varus position, the head of the first metatarsal raised in the case of TP dysfunction and remained on the ground in normal TP function. The purpose of this prospective study was to validate this clinical finding by surgical exploration, and to compare its sensitivity with other common clinical signs. Our series included 21 consecutive feet with TP tendon dysfunction (19 patients). The deformity was supple in 12 feet and fixed in 9 feet. Radiographs and magnetic resonance imaging were found to be unreliable in diagnosing dysfunction of the TP tendon. While other clinical signs (too many toes, the single-heel rise, and the double-heel rise) were noted to be negative in 20% to 35%, we found our first metatarsal rise sign to be positive in all cases of TP tendon dysfunction. This simple clinical test enables us to recognize and treat a dysfunction of the TP tendon at an early stage, when the foot is still supple. As the foot deformation progresses, early treatment may be the most effective measure in preventing long-term functional impairment.

Adolescent↗
PubMed1995

Total hip replacement with solid autologous femoral head graft for hip dysplasia.

Acetabuloplasty with solid autologous femoral head graft for the treatment of hip dysplasia is an established method which creates the contained cavity needed to accommodate the artificial cup. In order to evaluate the medium- and long-term results of this method using a cementless hemispheric cup, 34 patients (39 hips) operated on between 1979 and 1986 were clinically and radiologically reviewed. The minimal follow-up was 5 years (average 7.6 years). The Harris hip score increased from 36 points preoperatively to 89 points 1 year postoperatively and to 85.1 at the last follow-up. On roentgenographic evaluation, all grafts had been incorporated and appeared to have tolerated the mechanical loading well. Partial resorption of the graft occurred in 22 of the 39 hips, mainly in the lateral non-loaded zone. Twenty-nine of the 39 acetabular components showed migration, on average 4.2 mm cranially and 1.8 mm medially; 92% occurred during the first 2 years, and thereafter it was not progressive. Smaller cups migrated consistently more than larger cups. A significant correlation was found between cup migration and the degree of bone coverage of the cup, and extensive migration occurred in most cases with cup coverage by the host bone of less than 40%-50% of the weight-bearing surface of the cup. Only one acetabular component was altered significantly, and another appears to have become loose. The use of the normal-sized cups and cementless fixation medially in the primary acetabulum are thought to have contributed to our favorable mid- to long-term results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

In vitro kinematics of the axially loaded ankle complex in response to dorsiflexion and plantarflexion.

The rotational movements of the tibia and calcaneus that occur with dorsiflexion-plantarflexion and axial loading were studied in cadaver foot-leg specimens using an unconstrained testing apparatus. Independent of the foot flexion position, significant internal rotation of the tibia and eversion of the calcaneus were noted after the ankle complex was axially loaded. Independent of loading, 10 degrees of dorsiflexion resulted in 0.1 degrees of eversion and 2.1 degrees of internal rotation of the tibia. Conversely, 10 degrees of plantarflexion resulted in 1.6 degrees of inversion and 1.3 degrees of external rotation of the tibia. The induced rotational movements of the tibia and the calcaneus differed significantly between the specimens. These results suggest that the foot "axes" did not change by axially loading the ankle complex and they support previous reports that the ankle complex uses different axes for dorsiflexion and plantarflexion.

Aged↗
PubMed1995

Influence of ligament transection on tibial and calcaneal rotation with loading and dorsi-plantarflexion.

The purpose of this study was to quantify the effect of sequential ligament transection (anterior talofibular, calcaneofibular, posterior talofibular, deltoid, and subtalar interosseous ligaments) on the rotational movement of the tibia and the calcaneus as associated with axial loading and dorsi-plantarflexing the foot. Eight cadaver foot-leg specimens were investigated using a unconstrained testing apparatus. As the ankle complex was axially loaded, almost the same internal rotation of the tibia and the same calcaneus eversion was found with and without the various degrees of lateral and medial ligament release; additional sectioning of the subtalar interosseous ligament tremendously increased the resulting tibial and calcaneal rotation. While tibial and calcaneal rotation from foot dorsi-plantarflexing did not alter significantly with transection of the lateral ligaments, almost no tibial and calcaneal rotation occurred after additional sectioning of the deltoid and subtalar interosseous ligament. These results indicate that, after release of the lateral ligaments, the foot becomes partially mechanically disconnected from the tibia by additional transection of the medial ligaments and even further disconnected after transection of the subtalar interosseous ligament.

Aged↗
PubMed1995

Influence of arthrodeses on kinematics of the axially loaded ankle complex during dorsiflexion/plantarflexion.

The purpose of this study was to quantify the effect of selective arthrodesis (stabilization) of the ankle, subtalar, and talonavicular joints on the rotational movement of the tibia and the calcaneus occurring with dorsiflexion/plantarflexion. Six cadaver foot-leg specimens were investigated using an unconstrained testing apparatus. Simulated ankle joint arthrodesis caused a large increase in tibial rotation and calcaneal eversion-inversion. Subtalar and talonavicular stabilization did not cause as large a rotation.

Aged↗