Experimental Ankle Injuries: Analysis of the Traumatology of the Ankle Ligaments

On 32 osteoligamentous ankle preparations forced movements were performed in varying, accurately defined directions. the sequence in which this caused rupture of the individual ligamentous structures of the ankle is described. Dorsiflexion traumas predominantly injured the posterior part of the deltoid ligament, while in plantar flexion traumas the injuries primarily involved the anterior capsule and the anterior talofibular ligament. Internal rotation traumas injured the anterior talofibular ligament and the short, anterior fibres of the posterior talofibular ligament before the calcaneofibular ligament was damaged, whereas in adduction traumas the calcaneofibular ligament ruptured first. Forced external rotation primarily caused rupture of the deep structures of the deltoid ligament, while conversely abduction traumas first caused rupture of the superficial part of this ligament.     

Ligamentous influence in pelvic load distribution

Background context

The influence of the posterior pelvic ring ligaments on pelvic stability is poorly understood. Low back pain and sacroiliac joint (SIJ) pain are described being related to these ligaments. Computational approaches involving finite element (FE) modeling may aid to determine their influence. Previous FE models lacked in precise ligament geometries and material properties, which might have influence on the results.

Purpose and study design

The aim of this study is to investigate ligamentous influence in pelvic stability by means of FE using precise ligament material properties and morphometries.

Methods

An FE model of the pelvis bones was created from computer tomography, including the pubic symphysis joint (PSJ) and the SIJ. Ligament data were used from 55 body donors: anterior (ASL), interosseous (ISL), and posterior (PSL) sacroiliac ligaments; iliolumbar (IL), inguinal (IN), pubic (PL), sacrospinous (SS), and sacrotuberous (ST) ligaments; and obturator membrane (OM). Stress-strain data were gained from iliotibial tract specimens. A vertical load of 600 N was applied. Pelvic motion related to altered ligament and cartilage stiffness was determined in a range of 50% to 200%. Ligament strain was investigated in the standing and sitting positions.

Results

Tensile and compressive stresses were found at the SIJ and the PSJ. The center of sacral motion was at the level of the second sacral vertebra. At the acetabula and the PSJ, higher ligament and cartilage stiffnesses decrease pelvic motion in the following order: SIJ cartilage>ISL>ST+SS>IL+ASL+PSL. Similar effects were found for the sacrum (SIJ cartilage>ISL>IL+ASL+PSL) but increased ST+SS stiffnesses increased sacral motion. The influence of the IN, OM, and PL was less than 0.1%. Compared with standing, total ligament strain was reduced to 90%. Increased strains were found for the IL, ISL, and PSL.

Conclusions

Posterior pelvic ring cartilage and ligaments significantly contribute to pelvic stability. Their effects are region- and stiffness dependent. While sitting, load concentrations occur at the IL, ISL, and PSL, which goes in coherence with the clinical findings of these ligaments serving as generators of low back pain.     

Wrist: Current Diagnosis and Treatment of Scaphoid Fractures and Injuries of the Scapholunate Ligament

Summary BACKGROUND: Fractures of the scaphoid and injuries to the scapholunate ligament are mostly seen as causes of the acute and chronic painful wrist. Strict guidelines are necessary to precisely detect these lesions in the acute stage and to provide adequate treatment. A computed tomography bone scan parallel to the long axis of the scaphoid is best for demonstrating fractures and any associated deformities. Scapholunate ligament injuries are best staged by standard plane radiographs including stress views and by arthroscopy of the wrist. METHODS: To avoid lengthy plaster immobilization and to lower the risk of nonunion, displaced and comminuted scaphoid fractures of the wrist as well as all proximal pole fractures should be internally fixed. Headless screws such as the Herbert screw, now available in a cannulated shape, allow the minimally invasive stabilization of the majority of these fractures with a high success rate under early mobilization. Undisplaced fractures can be treated conservatively with a below-elbow cast; alternatively, they can be stabilized percutaneously without the need for immobilization in a cast. Early diagnosis of scapholunate ligament injuries is most important, as anatomical healing of the injured ligaments can be expected only with primary treatment including correct realignment of the scaphoid and lunate followed by immobilization in a cast for about 8 weeks. In cases of chronic lesions, ligament reconstruction or even partial wrist fusion can be performed. In order to assess the different procedures, precise classification and staging with regard to a dynamic or static pattern are needed. RESULTS: Early rigid fixation of scaphoid fractures promotes a union rate of up to 100 % with rapid functional recovery. Primary repair of scapholunate ligament injuries provides the best clinical outcome. Ligament reconstruction or partial wrist fusion can help to prevent rapid secondary arthrotic changes in the wrist and leads to significant pain relief, however with restriction of mobility and grip strength. CONCLUSIONS: Standardized diagnosis and treatment of scaphoid fractures and scapholunate ligament injuries improve clinical outcome and significantly reduce post-traumatic arthrotic changes in the wrist.     

Deltoid Ligament: Functional Analysis of the Medial Collateral Ligamentous Apparatus of the Ankle Joint

On 34 osteoligamentous ankle preparations the function of the various components of the deltoid ligament has been elucidated by tracing mobility patterns after successive transection of the components in varying sequence. The anterior and posterior talofibular ligaments were included in the study to investigate the interaction between these structures and the deltoid ligament. The tibiocalcaneal and the intermediate tibiotalar ligaments control abduction of the talus. The anterior tibiota-lar and talofibular ligaments control plantar flexion, while dorsiflexion is inhibited by the posterior tibiotalar and talofibular ligaments, and partly by the anterior talofibular ligament as well. In combination, the anterior and intermediate tibiotalar ligaments control external rotation, while the intermediate and posterior tibiotalar ligaments control both external and, together with the anterior talofibular ligament, internal rotation of the talus. Isolated, neither the anterior nor the posterior tibiotalar ligament appears to play any major role in ankle stability.     

Knee function following suture of fresh tear of the anterior cruciate ligament

A retrospective consecutive series of 60 patients treated with primary suture of knee ligament injuries is presented. All patients had an anterior ligament (ACL) tear. In 54 patients this injury was combined with a medial compartment tear. Four patients had isolated tears of the ACL. At follow-up after 4 years, 11 patients complained of instability, and in eight of these an anterolateral rotatory instability was demonstrated by the Slocum test. In contrast, only five of 49 patients with subjectively stable knees had positive Slocum tests. Thirty of 47 patients with negative Slocum tests had excellent function, compared with four of 13 patients with positive tests.