Rockwood Adults CH64

2862

SECTION FOUR • Lower Extremity

Technique

in dorsiflexion would result. However, an important cadaveric study has refuted this notion, finding no reduction in range of movement even when a syndesmosis screw was inserted in maximum plantarflexion. 388 Following fixation there has long been a tradition of removal of screws that cross the syndesmosis 43,65 due to concerns regard- ing a return to normal movement 272 and the inherent risk of screw fracture with this movement. Current practice among orthopedic surgeons appears to be for routine screw removal with 65% of surgeons reporting this to be their practice. 28 How- ever, the evidence for this is limited with only one small cohort study reporting improvements in functional scores following screw removal. 254 In contrast a large number of studies have found the reverse. Many authors have found no difference in range of movement 158 or functional outcomes 31,84,102,162 between those with intact, removed or broken screws, while others have reported better outcomes in those with fractured 133 or loose screws in comparison to those with intact syndesmosis screws. 234 Moreover, removal of syndesmosis screws places the patient at risk of complications. In a cohort of 76 patients Schepers et al. 334 reported an infection rate of 9.2%, a recurrence of the diastasis in 6.6% of patients with screw removal at a mean of around 3 months postoperatively and an overall complication rate of 22.4%. Others have confirmed this loss of reduction particu- larly when performed before 3 months post injury 139 although this has not always been found to result in an unstable ankle mortise 175 or affect functional outcomes. 162 A rare complication of tibial fracture following syndesmosis screw removal has also been reported. 63 A recent meta-analysis concluded that there is no place for routine removal of syndesmosis screws. 91 The other important decision is whether to allow patients to weight-bear in the initial postoperative phase. Photodynamic studies have shown significant alterations in force distribution in the tibia and fibula after syndesmotic disruption which per- sists after screw fixation, and in cadaveric studies application of axial force resulted in recurrence of the diastasis. 355 However, in a clinical study Hooper 158 described good outcomes with early weightbearing describing only loosening of the syndesmosis screw that did not appear to affect functional outcome.

✔ ✔ Syndesmotic Stabilization: KEY SURGICAL STEPS

❑ 2.5 cm skin incision placed anteriorly over syndesmosis, location confirmed with fluoroscopy ❑ Blunt dissection through fat then sharp incision through extensor retinaculum ❑ Expose and clear the syndesmosis ❑ Make a separate 2-cm incision laterally ❑ 2-mm K-wire joystick placed through lateral wound to reduce fibula ❑ Visual confirmation of recreation of a perfect “Mercedes-Benz” reduction of the articular surfaces ❑ Application of the reduction clamp ❑ Definitive fixation with a single 3.5-mm tricortical screw reaching, but not penetrating, the fourth cortex ❑ Wound closure Occasionally the syndesmosis can be reduced closed and screws placed percutaneously with a high degree of confi- dence in the reduction. Fluoroscopic studies indicate that comparisons with the contralateral, uninjured ankle, using a perfect lateral projection in particular, are helpful and can allow reduction within 2.5-mm displacement, particularly in expert hands. 189 Our preference, however, is to perform an open reduction. The patient is placed supine as described for fibular fixation. Using the image intensifier, the distal tibio- fibular joint is identified and a 2.5-cm longitudinal incision is placed directly over it. The skin is incised and blunt dissection is performed down to the retinaculum which is then incised longitudinally in line with the skin incision. The displaced joint is usually identified easily after clearance of hematoma. The joint margins of the distal tibiofibular joint are cleared to allow assessment of reduction, and the lateral aspect of the talar dome is visualized and inspected. The reduction itself is most conveniently performed by placing a heavy 2-mm K-wire percutaneously into the distal fragment to act as a joy- stick. This allows the distal fragment to be brought out to length, and translated or rotated into the incisura fibularis. The foot is held in a neutral position to confirm reduction and during fixation. The reduction is confirmed visually by the presence of a congruent “Mercedes-Benz”–shaped artic- ular margin between the tibia above, the talus medially and the fibula laterally (see Fig. 64-20). This is best seen with the ankle in neutral or slight dorsiflexion. Temporary sta- bilization is performed with a large periarticular reduction clamp, and checked fluoroscopically. Placement of the tibial tine anterior to the midline medially has been reported to minimize the risk of malreduction. 71 Definitive fixation is per- formed percutaneously with a single small fragment position screw through three cortices and just reaching, but not pen- etrating, the medial tibial cortex. The patient is instructed to remain nonweightbearing for 8 weeks and then enters unre- stricted progressive physiotherapy. The screw is not removed routinely.

Preoperative Planning

✔ ✔ Syndesmotic Stabilization:

PREOPERATIVE PLANNING CHECKLIST

❑ R adiolucent

OR table

❑ S upine with a bolster under the ipsilateral buttock

Position/positioning aids

❑ C ontralateral side

Fluoroscopy location

❑ 2 mm and 1.6 mm Kirschner wires, periarticular reduction clamp, small fragment screws

Equipment

❑ 250 mm Hg

Tourniquet

Other