(iii) Tarsometatarsal injuries—Lisfranc injuries

Tarsometatarsal/Lisfranc joint

Accurate early diagnosis with adequate reduction and maintenance of anatomic alignment of the dislocation or fracture within the Lisfranc joint complex have been found to be the key to successful outcomes regarding this injury. Because of the anatomic variations, the thin soft tissue envelop, and the abundance of ligamentous and capsular structures in the region, repair of these injuries can be a challenge. The classification systems used to describe these injuries aid in describing the mechanism of injury or displacement type present, which may aid in determining what treatment modality can provide the best outcome.

Ultrasound guidance for intra-articular injections of the foot and ankle

BACKGROUND

Ultrasound has been increasingly utilized in procedures involving intra-articular injections. This study's purpose was to compare the accuracy of intra-articular injections of the foot and ankle using palpation versus dynamic ultrasound in a cadaver model.

MATERIALS AND METHODS

Fourteen lightly embalmed cadaver specimens without notable osteoarthritis were used. A 0.22-gauge needle was placed by a foot and ankle orthopaedic surgeon into the first and second tarsometatarsal joints, subtalar joint, and ankle joint. The needle was initially placed using palpation, evaluated with ultrasound by an experienced rheumatologist, and re-inserted if necessary. Needle placement was confirmed with injection of an Omnipaque/methylene blue solution and examined under fluoroscopy, followed by dissection.

RESULTS

Palpation and ultrasound were 100% accurate in subtalar and ankle joint injections. Using palpation, the needle was correctly placed into the first TMT joint in three of 14 cadavers, and in four of 14 cadavers for the second TMT joint. Using ultrasound, the needle was correctly placed into the first TMT joint in ten of 14 cadavers, and into the second TMT joint in eight of 14 cadavers. When grouped, ultrasound was significantly more accurate for intra-articular needle placement compared to palpation in the midfoot (p = 0.003). On three specimens, dye extended beyond the second TMT joint.

CONCLUSION

Intra-articular injections of the subtalar and ankle joints can be successfully performed utilizing palpation alone. Ultrasound guidance significantly increases injection accuracy into the TMT joints compared to palpation alone and therefore US or Fluoroscopy is performed when injecting these TMT joints. When using selective diagnostic injections into a TMT joint to assess for the symptomatic joint and potential need for arthrodesis, the injected anesthetic may not remain isolated within that joint. These isolated TMT injections should not be done to answer that question without fluoroscopy confirmation with radiopaue dye demonstrating the injected fluid remained within the one joint of interest.

Assessment of the effects of diabetes on midfoot joint pressures using a robotic gait simulator

BACKGROUND

One of the more serious diabetic complications is Charcot neuroarthropathy (CN), a disease that results in arch collapse and permanent foot deformity. However, very little is known about the etiology of CN. From a mechanical standpoint, it is likely that there is a ;;vicious circle'' in terms of (i) arch collapse causing increased midfoot joint pressures, and (ii) increased joint contact pressures exacerbating the collapse of midfoot bones. This study focused on assessment of peak joint pressure difference between diabetic and non-diabetic cadaver feet during simulated walking. We hypothesized that joint pressures are higher for diabetics than normal population.

MATERIALS AND METHODS

Sixteen cadaver foot specimens (eight control and eight diabetic specimens) were used in this study. Human gait at 25% of typical walking speed (averaged stance duration of 3.2s) was simulated by a custom-designed Universal Musculoskeletal Simulator. Four medial midfoot joint pressures (the first metatarsocuneiform, the medial naviculocuneiform, the middle naviculocuneiform, and the first intercuneiform) were measured dynamically during full stance.

RESULTS

The pressures in each of the four measured midfoot joints were significantly greater in the diabetic feet (p = 0.015, p = 0.025, p < 0.001, and p = 0.545, respectively).

CONCLUSION

Across all four tested joints, the diabetic cadaver specimens had, on average, 46% higher peak pressures than the control cadaver feet during the simulated stance phase.

CLINICAL RELEVANCE

This finding suggests that diabetic patients could be predisposed to arch collapse even before there are visible signs of bone or joint abnormalities.

Technique tip: the use of a washer and suture endobutton in revision lisfranc fixation

Level of Evidence: V, Expert Opinion