Eversion, ankle

Prosthetic Feet. With the exception of partial foot amputees, the prostheses for all lower extremity amputees require a prosthetic foot. The prescription criteria for these feet take into consideration the amputation level, residual limb length, subject activity level, cosmetic needs, and the weight of the individual. Prosthetic feet range from the SACK (solid ankle cushioned heel) foot, which is relatively simple and inexpensive, to dynamic-response or energy-storing feet that are more complicated and considerably more costly. Note that prosthetic feet are often foot and ankle complexes. As such, prosthetic feet may replace plantarflexion/dorsiflexion, pronation/supination, and inversion/eversion. Prosthetic feet are typically categorized in terms of the function(s) they provide or replace and whether or not they are articulated. 

Nonarticulated feet are typically the simplest and least expensive. The foot and ankle are combined in a single component, and shock absoiption and ankle motion are provided by the materials and structure of the foot. Since these feet are nonarticulated, diey are quiet and typically require little maintenance. These feet are also cosmetic, lightweight, and provide good shock absorption and limited inversion/eversion on uneven terrain. Disadvantages of nonarticulated feet are the limited range of plantarflexion/dorsiflexion, difficulty with inclines due to heel compression, lack of adjustability for different heel heights, and little torque-absorption capability. 

Initial management should include a trial of anti-inflammatory medication, ankle bracing, and physical therapy. Many diagnostic tests are available. Sobel et al. popularized the peroneal tunnel compression test for longitudinal peroneus brevis tendon tears. This maneuver combines dorsiflexion and eversion of the foot and ankle with manual pressure on the peroneal tendons to elicit a painful response." Plain radiographs may demonstrate bony avulsions of the superior retinaculum or fractures. 

Rupture of the superior peroneal retinaculum, which extends from the lateral aspect of the distal fibular to the calcaneus, may result in peroneal tendon subluxation. Sometimes there is an associated avulsion fracture of the lateral aspect of the distal fibula. Typically, the patient will complain of painful clicking of the ankle, particularly on dorsiflexion and eversion of the foot. The diagnosis is often obvious... 

A thorough history, physical examination, and ancillary studies should be performed before treatment is instituted. The ankle joint is commonly involved in eversion and inversion strains or sprains, as well as in malleolar fractures. Dysfunction often follows immobilization treatment procedures. People with healed fractures may still have unresolved somatic dysfunctions. 

FIG. 100-4 High-velocity, low-amplitude thrusting technique for an eversion-inversion ankle somatic dysfunction. 

Fig. 16.51 a-e. Peroneal tendon instability (type III injury), a The patient presented with diffuse swelling and tenderness around the lateral ankle and complete inability to place his foot in eversion, b Internal oblique view of the ankle demonstrates a fibular flake fracture (arrowheads), c Transverse 12-5 MHz US scan obtained with the transducer applied transversely over the lateral malleolus (asterisk) reveals the avulsed bony fragment (arrowheads) and the anterior dislocation of the peroneus brevis (pb) and peroneus longus (pi) tendons, d Transverse 12-5 MHz US scan of the contralateral normal side, e Transverse T2-weighted MR imaging correlation confirms the anterior dislocation of the peroneal tendons... 

The motions of the ankle can be described in three orthogonal axes, which include axial rotation (intemal/extemal) in the transverse plane, inversion/eversion in the frontal plane, and dorsiflexion/plantarflexion in the sagittal plane (Figure 11.3). Motion along all three axes is pronation/ supination, where pronation is dorsiflexion, eversion and external rotation and supination is plantarflexion, inversion. 

FIGURE 11.3 Motions of the ankle in the sagittal plane (top from left to right neutral, dorsiflexion, plantarflexion), frontal plane (middle from left to right neutral, eversion, inversion), and transverse plane (bottom from left to right neutral, external rotation, internal rotation). 

The Newton ankle prosthesis (designed in 1973) was a two-part, nonconstrained prosthesis that had a UHMWPE tibial component with a flat proximal surface and a curved, cylindrical articulating surface [26, 27] (Figure 11.7). It has been described as a multiaxial joint that allows unrestricted motion about any of the three major axes [19]. The talar component comprised CoCr alloy and had a spherical articulating surface with a distal stem that was implanted into the talus. The result was an incongruent articulating surface that allowed dorsiflexion/plantarflexion, as well as slight inversion, eversion, and rotation [26, 27]. 

Cadaver studies have demonstrated changes in ankle biomechanics in normal ankles versus those implanted with STAR devices [69]. There were no significant differences in inversion/eversion. Dorsiflexion and plantarflexion were significantly reduced in STAR ankles. Significant increases in range of motion were observed during internal tibial rotation, while significant decreases in exterior tibial rotation were observed in the STAR ankles [69]. 

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