Residual kinematic deviations of the shoulder during humeral elevation after conservative treatment for mid-shaft clavicle fractures

Abstract

Despite residual functional deficits clinically observed in conservatively treated mid-shaft clavicle fractures, no study has reported a quantitative assessment of the treatment effects on the kinematics of the shoulder complex during functional movement. Using computerised motion analysis, the current study quantified the 3D residual kinematic deviations or strategies of the shoulder complex bones during multi-plane elevations in fifteen patients with conservatively treated mid-shaft clavicle fractures and fifteen healthy controls. Despite residual clavicular malunion, the patients recovered normal shoulder kinematics for arm elevations up to 60° in all three tested planes. For elevations beyond 60°, normal clavicle kinematics but significantly increased scapular posterior tilt relative to the trunk was observed in the patient group, leading to significantly increased clavicular protraction and posterior tilt relative to the scapula (i.e., AC joint). Slightly different changes were found in the sagittal plane, showing additional changes of increased scapular upward rotations at 90° and 120° elevations. Similar kinematic changes were also found on the unaffected side, indicating a trend of symmetrical bilateral adaptation. The current results suggest that shoulder kinematics in multi-plane arm elevations should be monitored for any compromised integrated motions of the individual bones following conservative treatment. Rehabilitation strategies, including muscle strengthening and synergy stability training, should also consider compensatory kinematic changes on the unaffected side to improve the bilateral movement control of the shoulder complex during humeral elevation.

Keywords: clavicle fracture; conservative treatment; motion analysis; range of motion; scapula.

FIGURE 1

Radiographs of a typical mid-shaft clavicle fracture (A) before and (B) after treatment with a sling and a figure-of-eight bandage.

FIGURE 2

Left: Photograph showing a participant with his arm elevated at 60 degrees in the scapular plane while the examiner applied the scapular locator to measure the scapular kinematics, and Right: Schematic diagram showing the measurement of the scapular kinematics during frontal-plane arm elevation using marker-based stereophotogrammetry. The bony landmarks of the trunk, namely, the spinal process of the 1st (T1), the 5th (T5), and the 8th thoracic vertebra (T8), were each identified by an infrared retro-reflective marker. The pose of the humerus was defined by the medial and lateral humeral epicondyles (MHE and LHE) and four additional technical markers (H1-H4). The scapular pose was identified by the scapular locator, with the palpation rods adjusted to fit over the root of the scapular spine (RS), the acromial angle (AA), and the inferior angle (IA) of the scapula.

FIGURE 3

Mean rotational angles of the scapula (A–C), clavicle (D,E), and the acromioclavicular (AC) joint (F–H) during frontal-plane arm elevation for both the patient (black bars: affected side; grey bars: unaffected side) and control (white bars) groups. Significant differences between the affected side and healthy control are indicated by the symbol *, while significant differences between the unaffected side and healthy control are indicated by the symbol +. Standard deviations are shown as error bars.

FIGURE 4

Mean rotational angles of the scapula (A–C), clavicle (D,E), and the acromioclavicular (AC) joint (F–H) during scapular-plane arm elevation for both the patient (black bars: affected side; grey bars: unaffected side) and control (white bars) groups. Significant differences between the affected side and healthy control are indicated by the symbol *, while significant differences between the unaffected side and healthy control are indicated by the symbol +. Standard deviations are shown as error bars.

FIGURE 5

Mean rotational angles of the scapula (A–C), clavicle (D,E), and the acromioclavicular (AC) joint (F–H) during sagittal-plane arm elevation for both the patient (black bars: affected side; grey bars: unaffected side) and control (white bars) groups. Significant differences between the affected side and healthy control are indicated by the symbol *, while significant differences between the unaffected side and healthy control are indicated by the symbol +. Standard deviations are shown as error bars.

FIGURE 6

Schematic diagram showing the different kinematics of the scapula and the AC joint between the patient (red lines) and healthy control (black dash lines) groups in the transverse plane (A) and sagittal plane (B) during frontal-plane arm elevation. Compared to healthy controls, the patient group showed increased scapular protraction and posterior tilt while maintaining unaltered scapular rotation.