Rockwood Adults CH64

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CHAPTER 64 • Ankle Fractures

the standard fragment screw will be easier to locate, particularly if the procedure is performed under local anesthesia in the out- patient setting. The position of the screw has also been a matter of debate; McBryde et al. 238 found that a screw placed 2 cm proximal to the ankle affords more stability than a more proximal screw while Kukreti et al. 202 found no difference in functional outcomes in patients with screws placed at or just proximal to the syndesmosis. The use of bioabsorbable screws across the syndesmosis has been reported with good functional and radiographic results. 8,161 A cadaveric biomechanical study found a 5-mm bioabsorbable screw to have equal strength to a 5-mm stainless steel screw. 78 Of note, none of the clinical studies report osteolysis or foreign body reaction although irritation due to incompletely absorbed screw heads has been reported. 8,181 An alternative option for syndesmotic fixation is the use of a suture or wire construct held in place by cortical metal but- tons. Early reports of the use of this method found good clinical results but lower pull-out strength on biomechanical testing. 338 Some investigators have reported equal biomechanical proper- ties with sutures or screws on application of an external rotation force 380 while others have reported significantly increased syn- desmosis widening on external rotation with the suture com- pared to a screw. 117,193 The semirigid nature of this device may more closely approximate the uninjured syndesmosis: Some biomechanical reports suggest movement at the syndesmosis during cyclical loading is similar to that seen in intact syndes- moses, 188,373 although other investigators have reported non- physiologic movement at the syndesmosis with both screws and suture constructs. 349 A number of small studies have looked at the use of a commercially available device, the “Ankle Tight- rope,” with generally good results. Small cohort studies with follow-up of up to 2 years have reported good functional and radiologic results that are equivalent to, or in some cases better than, equivalent cohorts treated with screws. 73,88,269,311,320 The major complications with the device have been related to the suture knot, 320 infection, 320 problems with inflammation, 415 irri- tation, 311 osteolysis, 88 sinus formation, 269 and fracture through the suture tract. 153 Given the difficulty in identifying syndesmotic anatomy with two-dimensional fluoroscopy, it is not surprising that closed reduction results in a malreduction in around half of cases of standard syndesmotic fixation. 300 Open reduction allows a more predictable result, although the rate of malreduction remains surprisingly high at around 15%. 252,326 The Tightrope may have an advantage in this regard, with two contradictory RCTs comparing screws with suture button devices. Naqvi et al. 268 reported more accurate syndesmosis reduction with a tightrope than with screws, while Kortekangas et al. 193 found no differ- ence in reduction accuracy. Neither author found any func- tional differences at two years postoperatively. The position of the foot while the syndesmosis screw is inserted has been the subject of controversy. It was initially suggested that because of the shape of the talus, and to pre- vent overtightening of the screw and subsequent stiffness of the ankle, that the screw should be inserted with the ankle in dor- siflexion. Olerud 281 reported that for each 10-degree increase in plantarflexion during insertion, a 1-degree residual deficit

✔ ✔ Posterior Malleolar Fixation With Posterior Plate: KEY SURGICAL STEPS ❑ 10–15 cm longitudinal skin incision just to lateral side of tendo Achilles (TA) ❑ Perform blunt dissection through fat to avoid sural nerve injury ❑ Sharp incision through deep fascia of the leg ❑ Identify plane between peroneal tendons laterally, and flexor hallicus longus medially ❑ Elevate FHL medially and retract to expose the posterior malleolar fragment ❑ Elevate fragment, avoiding damage to PITFL, to expose fracture ❑ Remove loose fragments and reduce any impaction ❑ Replace fragment, using cortical read at the apex to guide reduction ❑ Temporarily secure with Kirschner wire just above plafond, then apply plate in buttress mode ❑ Move peroneal tendons medially to expose the fibular fracture ❑ Reduce and fix fibular fracture with posterior 1/3 tubular plate, or T-plate ❑ Close skin Syndesmotic Stabilization Syndesmotic stabilization can be achieved with the use of screws, suture techniques, staples, 237 and bolt fixation. 85 Screw fixation is most widely practiced, with 51% of orthopedic sur- geons using 3.5-mm screws, penetrating three of four cortices (67%) with equal numbers of surgeons preferring one or two screws (44% each). 28 Fourteen percent of surgeons are reported to use a suture device routinely. 28 Biomechanical testing has reported conflicting results. Xenos et al. 421 found that two screws conferred significantly greater strength to the syndesmosis than one, whereas Thompson and Gesink 375 found no significant difference when comparing syn- desmotic fixation with a 3.5-mm screw to a 4.5-mm screw. Hansen et al. 135 found 4.5-mm screws were able to withstand shear stress better than 3.5-mm screws. Biomechanical testing has not demonstrated a difference between the use of screws spanning either three or four cortices in strength 34 or range of movement following fixation. 277 Clinical studies have also not demonstrated the superiority of any particular technique. Wikerøy et al. 413 found no differ- ence in functional results at 8 years between those fixed with one screw spanning four cortices or two tricortical screws. Høiness and Strømsøe, 156 although reporting significantly bet- ter short-term functional outcomes in those with two 3.5-mm tricortical screws in comparison to those with one 4.5-mm screw spanning four cortices, reported that by 1 year there was no significant difference between groups. Interestingly Moore et al. 262 found good outcomes with fixation spanning either three or four cortices but reported a higher rate of recurrence of the diastasis when weight-bearing instructions were ignored by patients with three-cortex only fixation. Finally four-cortex fix- ation exposes the patient to an additional risk of complications with case reports of posterior tibial tendon tear caused by dam- age from the tip of the screw. 204 Pragmatically, small fragment screws have a smaller head that is less likely to cause irritation later, while if elective removal is anticipated, the larger head of