The effect of partial deltoid ligament injuries on the external rotation stability: A cadaveric study

BACKGROUND

The anterior and posterior part of the deltoid ligament have different functions during ankle flexion motion. Partial ligament injuries have been demonstrated in previous clinical reports. However, the efficacy of external rotation stress test in partial injured cases is unavailable till now.

METHODS

Thirty-two fresh cadaveric specimens were included and allocated into two destabilization groups. In the first group, the anterior portion of deltoid ligament (DL) and syndesmotic ligament were sequentially severed, while in the second group, the posterior portion of DL and syndesmotic ligament were sequentially severed. Mortise view radiographs were taken after each destabilization stage when the ankles were placed at plantarflexion and dorsiflexion positions and stressed in standard external rotation force. The medial clear space (MCS) and talar tilt (TT) angle were measured and compared among different destabilization stages.

RESULTS

When the ankles were placed at neutral position, the TT significantly increased in all destabilization stages. The MCS significantly increased after the partial deltoid ligament ruptures only with presence of syndesmotic ligament injuries. There was no significant difference of MCS at plantarflexion for all stages of destabilization if the anterior portion of DL is preserved. Similarly, no significant increase of MCS was detected at dorsiflexion if the posterior portion of DL and posterior inferior tibiofibular ligament are intact.

CONCLUSION

Partial DL rupture causes ankle rotational instability at different ankle joint positions, especially when combined with syndesmotic injuries. The neutral position is recommended for diagnosis of partial DL ruptures under external rotation stress.

Characteristics of medial gutter arthritis on weightbearing CT and plain radiograph

OBJECTIVE

An ankle arthritis with medial gutter obliteration is known to have good results after joint preservation surgery. However, the diagnosis is often missed on radiographs. The aims of this study were to investigate sensitivity of radiographs in the identification of medial gutter arthritis, incidence and direction of the talar tilt on weightbearing CT (WBCT), and to assess radiographic alignment of the medial gutter arthritis.

MATERIALS AND METHODS

Radiographic data was retrospectively evaluated in 102 ankles which were diagnosed medial gutter arthritis by using the WBCT at our clinic between January 2017 and June 2019. Among the 102 ankles, proportion of ankles which showed medial gutter arthritis on plain radiograph was obtained. The presence and direction of talar tilt were assessed on three coronal WBCT images at the anterior, middle, and posterior aspect of the ankle. Plain radiographic parameters were compared between the 102 ankles and control group.

RESULTS

Plain radiograph showed medial gutter arthritis only in 63 ankles (62%) among the 102 ankles. Most of the ankles with medial gutter arthritis showed talar tilt on WBCT, and about half of all ankles showed valgus talar tilt at the anterior aspect of ankle on WBCT. In ankles with medial gutter arthritis, the mechanical axis of the lower extremity and the tibial plafond were varus angulated and the talus was medially translated compared to the control group.

CONCLUSION

Radiographs were less sensitive than WBCT in demonstrating medial gutter arthritis. Anterior aspect of ankles with medial gutter arthritis often showed valgus direction of talar tilt. Varus mechanical axis deviation and varus tibial plafond are commonly associated with the medial gutter arthritis.

Individuals with both perceived ankle instability and mechanical laxity demonstrate dynamic postural stability deficits

BACKGROUND

Chronic ankle instability is a frequent and serious consequence of lateral ankle sprains. The contribution of perceived instability and potential for mechanical laxity to contribute to the overall deficit in dynamic postural stability is unclear. The purpose was to determine if those with mechanical laxity demonstrated significant differences in dynamic postural stability compared to controls, copers and those with perceived instability.

METHODS

Of 93 participants, 83 recreationally active individuals were divided into 4 groups: controls, copers, those with perceived instability, and those with both perceived instability and mechanical laxity. Injury history and the Cumberland Ankle Instability Tool were collected, and an instrumented arthrometer was applied. Participants completed a single limb jump landing, balancing upon completion. Ground reaction force data were collected, scaled to body mass, and the Dynamic Postural Stability Indices were calculated for anterior-posterior, medial-lateral, vertical and composite. One-way ANOVAs with Tukey post-hoc tests (α<0.05) were conducted on each of the stability indices among the four groups.

FINDINGS

The mechanically lax group had significantly greater mean (standard deviation) medial-lateral stability index scores 0.57 (0.62) than the coper group 0.24 (0.20; P=0.02) and significantly greater composite index scores 0.73 (0.57) than the perceived instability 0.49 (0.09) and coper groups 0.47 (0.12 P=0.05). No other indices were significantly different among groups.

INTERPRETATION

Individuals with perceived instability and mechanical laxity exhibited dynamic postural deficits compared to copers and those with perceived instability alone. Mechanical laxity may contribute to the deficits in dynamic postural stability.