Stable anatomic fixation of the lateral malleolus fragment is highly appreciated to achieve satisfactory results in ankle fractures.
Yablon et al (17) pointed out that the talus follows the lateral malleolus so the minor displacement of lateral malleolus fractures leads to talar shift and joint incongruity.
Various methods of lateral malleolar fixation have been utilized, all with acceptable results. Most commonly buttress plating and\or a lag screw. this provides reliable fixation and maintains the length and rotation of the lateral malleolus. It is preferred in comminuted fractures, as length could not be reliably maintained with an intramedullary screw as well as fractures with a syndesmotic injury where a syndesmotic screw is needed (Weber type C). The complications of plate fixation of the lateral malleolus are wound healing; especially in swollen ankles and painful prominent hardware often develops late. The reduction of the fracture may be done in a closed or open manner. (18) Advantages of closed reduction include minimal soft-tissue dissection, short operative time, no need for tourniquet if isolated lateral malleolus fractures, improved healing and shortened rehabilitation time
Because the fracture hematoma is not violated. (13) The long intramedullary screw allows getting a purchase within the fibular canal, therefore eliminating hardware migration. The intramedullary position allows for dynamic compression at the fracture site with weight-bearing, thus enhances fracture healing. (15) The slight flexibility of the axial screw allows it to easily accommodate the distal fibular bow, resulting in three-point fixation of the fracture, as the lateral malleolus is normally in 10 to 15 degrees of valgus to the fibular shaft. (18)
A biomechanical study by Bankston et al for evaluation of intramedullary screw versus buttress plate and lag screw. The fractures were fixed with one of the fixation methods and then placed under a torsional load to failure. It was found that the intramedullary screw provided 66.5% of the strength of native bone while the lateral buttress plate provided 61.5%. This was not statistically significant, but it did prove that an intramedullary screw provides stable fixation. So, rehabilitation can be started early without the risk of loss of reduction. (15)
This study includes the postoperative evaluation of closed reduction and percutaneous internal fixation of unstable lateral malleolus fractures Weber types A or B with an intramedullary, 3.5 mm, fully threaded, self-tapping screw with a washer. Regarding the results, 64% of patients had excellent results, 32% had good results and 4% had fair results. The mean of the score was 93 ± 8.717 ranging from 60 to 100.
The results of this study are comparable with the results of Ray TD et al (18) which included 24 patients treated with closed reduction and percutaneous internal fixation with an intramedullary, fully threaded, self-taping screw. At the final follow-up, 42.1% had an excellent result, 42.1% had a good result, 5.3% had a fair result and 10.5% had a poor result.
The results of the present study are also comparable with the results of Latif G et al which included 46 patients with displaced lateral malleolus Weber A and low Weber B fractures who underwent closed reduction and percutaneous internal fixation with an intramedullary, 3.5 mm, fully threaded, self-tapping bone screw were
retrospectively reviewed. the results were excellent in 25 patients (54.3%), good in 20 patients (43.5%) and fair in one patient (2.2%). (13)
In the present study, the average time for union was 5.86 ± 1.74 weeks, ranging from 4 to 8 weeks with a rate of union 100%. While in the study of Ray TD et al (18), the average time of fracture union was 8.2 weeks with one case developed nonunion, with a union rate of 95.5%. The average time of full weight-bearing was 6.8 weeks and in patients with isolated lateral malleolus fractures time decreased to 4.5 weeks. The same results in the study of Latif G et al (19), the average time of union was 8.2 weeks. The average time to full weight-bearing was 6.8 weeks and 4.5 weeks in patients with isolated lateral malleolus fractures.
Regarding the use of tourniquet, in the present study no tourniquet is used, except in the three cases with associated medial malleolar fractures who underwent open reduction and internal fixation. Medial malleolus fracture was fixed by 2 cancellous screws in two patients while the third patient had his medial malleolus fixed with a plate and screws.
In the study of Ray TD et al (18) and Latif G et al (13), using this percutaneous technique, the use of a tourniquet is optional, and they didn’t report the use of tourniquet in isolated lateral malleolus fractures. But in the study of Kim HJ et al, who used a 3.5 mm T-shaped locking compression plate, the conventional lateral approach was utilized to expose the lateral malleolus under tourniquet, and they didn’t report any postoperative tourniquet complications. (19) In the study of Lamontagne J et al (20), who used the lateral plate and anti-glide plate techniques, all the cases are operated under tourniquet, despite all of them are isolated lateral malleolus fractures. The mean tourniquet time in group 1 treated with lateral plate was 48.5 minutes and in group 2 treated with anti-glide plate was 44.3 minutes, also they didn’t report any postoperative tourniquet complications. (20)
The use of tourniquet may lead to many complications as Nerve injury which is the most common complication. ranging from mild transient loss of function to irreversible paralysis. Other complications of a tourniquet include arterial injury due to indirect trauma and thrombosis, tourniquet pain, compartment syndrome, pressure sores, deep venous thrombosis, High pressures and missed digital tourniquets can lead to severe ischemia of the digits. (21)
The length of the screw used in the present study ranging from 90 mm to 110 mm. In the study of Ray TD et al (18), the length of the screw ranged from 62.5 mm to 100 mm depending on the location of the fracture, pattern and the width of the medullary canal proximal to the fracture site. While in the study of Latif G et al (19), the length of the screw varied between 100 mm and 120 mm, depending on the fracture location and pattern. In this study, the length of the screw didn’t affect the results.
The small set 3.5 mm screw used in this study was long enough to get a purchase within the fibular medullary canal, with available screw length measures ranging from 60 mm to 120 mm. The flexibility of the 3.5 mm screw allowed it to accommodate the distal fibular bow, resulting in three-point contact within the fibular medullary canal. The small set 4.0 mm screw, either fully threaded or partially threaded, didn’t have available length measures to get a purchase in the fibular medullary canal. The standard 6.5 mm screw, either fully threaded or partially threaded, is a rigid screw and not flexible to accommodate the distal fibular bow. So, the 4.0 mm and 6.5 mm screws can’t be used in this study.
The age and sex of the patients were not statistically significant, which was proven in this study and other studies that were done by other authors. (13,18)
Of the twenty-five patients in the present study, three patients had associated medial malleolus fractures. While in the study of Ray TD et al (18), five patients had an associated medial malleolar fracture and one patient had a trimalleolar fracture. Two of the patients with associated medial malleolus fractures had an unsatisfactory result, one patient with fair score had a malunited medial malleolus and one patient with poor score had an ununited medial malleolus. But in the study of Latif G et al (13), fifteen patients had an associated fracture of the medial malleolus and ten patients had a trimalleolar fracture as well as in the study of Kim HJ et al (19), eleven patients had associated medial malleolar fractures. But both studies didn’t report the correlation between associated fractures and the final score. The study of Lamontagne J et al (20) was on isolated lateral malleolus fractures.
In this study, three patients had associated medial malleolus fracture. Two of them had satisfactory results, the remaining one had a fair score with mild pain and edema with activity and was able to walk the desired distance with mild limp despite the full range of motion of ankle joint.
In the present study no single case complicated with nonunion. But, one patient had malunited lateral malleolus fracture in the form of rotation. Rotation most probably occurred during screw head tightening at the end of its insertion which might be due to early removal of the bone holding clamp with partial loss of fracture reduction. however, malunion didn’t affect the results. While in the study of Ray TD et al(18), one patient with a fair score who had a shortened lateral malleolus ≤ 2 mm. Another patient with a poor score who developed nonunion, which was internally fixed in distraction during ipsilateral closed intramedullary tibial nailing and was managed later by bone graft and plating. In the study of Latif G et al (13), one patient, who had a fair score, developed malunited lateral malleolus in the form of shortening.
The overall infection rate in the present study was 4%, which were two patients with a superficial infection managed by daily dressing and adequate antibiotic. When compared to the study of Ray TD et al, one patient (4.2%) developed minor wound complications in the form of mild serous discharge from the operative site at the time of cast removal which response to conservative management. No superficial or deep infection was reported in the study of Latif G et al (13).
In the study of Lamontagne J et al (20), who used the lateral plate and anti-glide plate techniques, eleven patients had wound infection with an infection rate of 5.7%. Nine of them had a superficial infection and two of them had deep infection. One of them treated with surgical debridement and an antibiotic bead pouch technique and the wound was closed with the removal of the bead pouch, five days later. The second patient had a chronic infection. Wound dehiscence and reflex sympathetic dystrophy complicated the early postoperative period. The plate was removed after two years to control an open draining sinus. While in the study of Kim HJ et al, no infection rate was reported despite the cases was treated with open internal fixation with the lateral skin incision.
The present study and the studies of Ray TD et al (18) and Latif G et al (13) had a low infection rate when compared to the study of Lamontagne J et al (20), this might be due to the closed
reduction method and the percutaneous technique in fixation of lateral malleolus fractures through just a 1 cm skin incision without interruption of soft tissue like the traditional lateral skin incision in open internal fixation.
Of the twenty-five cases in the present study, the studies of Ray TD et al (18) and Latif G et al (13), no one had a painful, prominent screw or peroneal tendinitis due to the intramedullary position of the screw. In Kim HJ et al study, there was no peroneal tendinitis. But, six cases (23.1%) had implant irritation over the operative site.
In laterally applied plates hardware-related problems were more common. Brown et al reported that 31% of patients had hardware related pain and that 23% of patients required hardware removal, 50% of those patients who had their hardware removed reported improvement and a decrease in pain score. (22)
Jacobsen et al reported that 66% of patients with a lateral plate had implant-related complaints that led to the removal of implants. 75% of these patients had relief after removal. (23) Tornetta and Creevy also reported that 56% of patients with a lateral plate had complaints of palpable hardware, 17% had pain related to the plates, 15% had a restriction in movements and 31% required removal of implants. (24)
Ostrum reported no wound problems, no palpable hardware, no nonunion or implant problems but noticed transient peroneal tendinitis in 4 patients and only 2 patients required removal of the implant in posterior plating of displaced fibula fractures. (25) Furthermore, 43% of plates were removed because of peroneal tendonitis in Weber and Kraus. (26)
The results of this study, which was also supported by many other studies proved that percutaneous fixation gave good clinical results in the management of lateral malleolus fractures Weber types A or B with minimal complication rate and doesn’t need another surgery for hardware removal. (13,18)