SUPERIOR PERONEAL RETINACULUM INJURY
The superior peroneal retinaculum (SPR) forms the roof of the superior peroneal tunnel. The tunnel contains the peroneus brevis and longus tendons and is bordered by the retromalleolar groove of the fibula and the lower aspect of the posterior intramuscular septum of the leg.69,70 The SPR originates from the posterolateral ridge of the fibula and inserts onto the lateral calcaneus, and it is the primary restraint of the peroneal tendons within the retromalleolar sulcus.
Injury to the retinaculum results from both ankle dorsiflexion and inversion, and forceful reflex contraction of the peroneal muscles, which causes subluxation or dislocation of the contained tendons.69 A high level of suspicion is required regarding these injuries since the mechanism of injury is similar to that of a simple lateral ankle sprain. In the setting of retrofibular pain, snapping or popping sensations around the lateral malleolus, or chronic ankle instability that worsens on uneven surfaces, one must consider an injury to the SPR.69 Radiographs are not always diagnostic; however, occasionally on an internal rotation view, one may see a cortical avulsion off the distal tip of the lateral malleolus (“fleck sign”) indicating a rim fracture from an SPR injury (Figure 7). MRI is the best imaging modality to assess the peroneal tendons, as well as an SPR injury. Recently, ultrasound has grown in popularity and may be more useful, since it allows for dynamic evaluation of subluxating/dislocating tendons.69
Conservative management is often associated with poor outcomes, and surgery is indicated for all acute and chronic dislocations in athletes.71 Anatomic reconstruction of the SPR is the preferred surgical method.72 Peroneus brevis debulking and fibular groove deepening may also augment the retinaculum repair.73 van Dijk and colleagues in their systematic review showed that patients treated with both groove deepening and SPR repair have higher rates of return to the sport than patients treated with SPR repair alone.74
Fifth metatarsal stress fractures usually occur secondary to lateral overload or avulsion of the peroneus brevis. The fifth metatarsal base can be susceptible to injury in a cavovarus foot. Non-operative treatment typically requires a longer period of immobilization (boot or cast) and necessitates a longer period of non–weight-bearing (anywhere between 6-12 weeks). Therefore, surgery is typically recommended in athletes or in the setting of a recurrent base of the fifth metatarsal fracture to expedite healing and return to play. Return to play is still not recommended until there is evidence of radiographic healing of the fracture. There are certain distinctions with fifth metatarsal stress fractures regarding location and healing rates that need to be taken into account.75,76 In particular, zone 2 injuries (Jones fractures) represent a vascular watershed area, making these fractures prone to nonunion with nonunion rates as high as 15% to 30%. Occasionally, the cavovarus deformity will require correction as well as a reduction in the risk of recurrence or nonunion. Surgical fixation most commonly consists of a single screw placed in an antegrade fashion.77 One must pay attention to screw size since smaller diameter screws (<4.5 mm) are associated with delayed union or nonunion. Moreover, screws that are too long will straighten the curved metatarsal shaft and can lead to fracture distraction or malreduction (Figures 8A, 8B).77
Patients have returned to competitive sports within 6 weeks; however, it should be noted that causes of failure were linked to early return and return to sports before a radiographic union can lead to failure of fixation. Ekstrand and van Dijk78 studied a large group of professional soccer players and found that out of 13,754 injuries, 0.5% (67) were fifth metatarsal fractures. Of note, they found that 45% of players had prodromal symptoms. Furthermore, after surgical treatment the fractures healed faster, compared with conservative treatment (75% vs 33%); however, there was no significant difference in lay-off days between both groups (80 vs 74 days).78 Matsuda and colleagues79 looked at 335 male collegiate soccer players, 29 of whom had a history of a fifth metatarsal stress fracture. They found that playing the midfield position and having an everted rearfoot and inverted forefoot alignment were associated with fifth metatarsal stress fractures.79 Saita and colleagues80 found that restricted hip internal rotation was associated with an increased risk of developing a Jones fracture in 162 professional football players. Finally, Fujitaka and colleagues81 looked at 273 male soccer players between 2005 and 2013. They found an association between weak toe-grip strength and fifth metatarsal fractures, suggesting that weak toe-grip may lead to an increase in the load applied onto the lateral side of the foot, resulting in a stress fracture.81
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