Abstract
Purpose:
This study aimed to investigate the therapeutic effects and complications of minimally invasive surgery in treating displaced avulsion fractures (2–3 mm) of fifth metatarsal base zone I in young adults or athletes.
Methods:
Forty-six patients with displaced fifth metatarsal base avulsion fractures were assigned to operative and nonoperative groups by randomization. Patients in nonoperative group were immobilized with plaster, while patients in operative group were treated with closed reduction and fixation with a percutaneous screw.
Results:
All patients were followed up for 14 months on average (ranging from 12 to 24 months). All cases got primary union except for three patients in nonoperative group with malunion and two with frequent mild to moderate plantar pain. The American Orthopaedic Foot and Ankle Society score was significantly better in operative group at 6 months after treatment (p < 0.05) but not significantly different at 12 months after treatment (p > 0.05). The average time of full weight bearing and returning to work was significantly shorter in operative group than nonoperative group (p < 0.05).
Conclusion:
In young adults or athletes with displaced avulsion fractures of fifth metatarsal base zone I, closed reduction and percutaneous screw fixation provides anatomical stable fixation and early mobilization.
Brief introduction
Among fractures of foot, fracture of proximal portion of the fifth metatarsal is a common kind. It takes up two-thirds of the fifth metatarsal fracture and is usually a low-energetic injury after a fall or twist. 1 The mechanism of injury was believed to be an abduction force on the forefoot with simultaneous ankle plantar flexion. 2,3
The management of fifth metatarsal base fractures, specifically zone I fractures, continues to be a controversial topic. Some experts prefer conservative treatment for simple displaced avulsion fracture of the fifth metatarsal base. A number of conservative treatments have been reported, such as a hard-soled shoe with elasticated bandaging, immobilization with a cast, and a walking boot. Several studies demonstrated that conservative management could have satisfactory outcomes. 2,4 –15 Studies about simple displaced avulsion fracture of the fifth metatarsal base demonstrated that fracture with mild displacement (displacement <3 mm) should be fixed for 3 weeks with conservative treatment. 12,16
In contrast, some studies showed that conservative treatment might not produce optimal long-term outcomes and result in delayed union and returning to activities in athletic patients with displaced fifth metatarsal base zone I avulsion fracture. 2,5 There were also studies 16 –18 which suggested that only anatomic reduction and fixation could reconstruct the indispensable function of the fifth metatarsal base especially in active young adults and athletes.
As the most lateral one, the fifth metatarsal bone is an important component of the longitudinal and transverse arch of lateral column, which plays an important role in stress conduction and weight bearing of mid-foot. Young adults and athletes are active, making necessary the integrality of the fifth metatarsal.
Being the end point of peroneus brevis, fibularis tertius, and lateral plantar fascia, the fifth metatarsal base fracture is the most common type in metatarsal fracture, especially the fifth metatarsal base avulsion fracture. Thus, inappropriate treatment may cause consequent pain and affected gait. This study aimed to investigate the therapeutic effects of a novel surgical technique on displaced fifth metatarsal base zone I avulsion fracture in young adults and athletes, comparing with conservative treatment.
Materials and methods
The study protocol was approved by the ethics committee of Tongji Hospital. Informed consent was signed by each enrolled objective.
Study design
From January 2009 to January 2015, a total of 46 patients with displaced (2–3 mm) fifth metatarsal base avulsion fracture (Figure 1(a)) were included. Five patients (11%) lost to follow-up at 12 months after treatment. According to inclusion criteria, patients were allocated to operative group or nonoperative group by randomization. During enrollment, each patient got a randomized number generated by the computer. Twenty-one patients with odd numbers were assigned to the operative group and the other 20 patients with even numbers to the nonoperative group. If a patient did not agree to enter the corresponding group, the patient was excluded from this study.
(a) The fifth metatarsal base avulsion fracture confirmed by X-ray. (b) The X-ray after surgery. A hollow screw of 3.0 mm was tapped. (c) The X-ray 12 months after surgery. (d) The fifth metatarsal base avulsion fracture confirmed by CT scan. (e) The incision of 1 cm made at the entry point of Kirschner wire. (f) The Kirschner wire penetrated through the vertex of the fifth metatarsal proximal tuberosity along the fracture line till the contralateral cortex percutaneously. CT: computed tomography.
Inclusion criteria were as follows: patients with displaced (2–3 mm) fifth metatarsal base avulsion fracture (Figure 1(a) and 1(d)), patients aged 18–35 years (young adults or athletes), and patients with fracture within 2 weeks. Exclusion criteria were as follows: patients with other metatarsal fracture besides the fifth metatarsal fracture, patients with open fracture, patients with pathological fracture, patients with osteoporotic fracture, or patients with a history of surgery on the affected foot or ankle.
Average age was 25.57 ± 6.98 years for those in the operative group, and 28.71 ± 7.52 years for those in the nonoperative group. Both groups showed no statistical difference in age (p = 0.175) and gender (p = 0.421). Demographic profiles of both groups are shown in Table 1. Forty-one patients were included eventually, including 26 men and 15 women. Sixteen patients were athletes with mild to moderate training schedule every day before injury (eight in the operative group and eight in the nonoperative group). The cause of all injuries was simple sprain. Among the enrolled patients, 38 patients were diagnosed with isolated metatarsal fracture and 3 patients with metatarsal and distal radius fracture (2 in operative group and 1 in nonoperative group). The three patients with distal radius fracture were treated with open reduction and internal fixation with plates. All patients were treated within 7 days after injury.
Demographic profiles of both groups.
AOFAS: American Orthopaedic Foot and Ankle Society; VAS-FA: Visual Analog Scale–Foot and Ankle.
a p < 0.05 operative group versus nonoperative group.
Surgical technique
All procedures were performed by the same surgeon. Under subarachnoid anesthesia or continuous epidural anesthesia, the surgery was aided with a thigh tourniquet. Closed reduction was conducted with a pointed reduction clamp under C-arm guidance. One tip of the clamp is placed proximally at the inferior side of the fifth metatarsal base to avoid sural nerve injury, and the other tip is placed distal to the fracture site, along the metatarsal shaft. A Kirschner wire (Figure 1(f)) was penetrated through the vertex of the fifth metatarsal proximal tuberosity along the fracture line till the contralateral cortex percutaneously. An incision of 1 cm was made at the entry point of Kirschner wire (Figure 1(e)). Incision should be made at the plantar side of the fifth metatarsal base in order to avoid sural nerve injury. Then the soft tissue was distracted by a vessel clamp. After a hole was drilled, a hollow screw of 3.0 mm was tapped (Figure 1(b)). The screw should penetrate the contralateral cortex.
Patients in nonoperative group were immobilized with a cast at a neutral position. A short leg cast was applied for 2 weeks, thereafter a tube-type gypsum was used for the next 2–4 weeks before weight bearing. Moderate movements of the knee and hip were encouraged to avoid venous thrombosis and musculoskeletal atrophy of lower extremity during immobilization.
Postoperative rehabilitation
Affected limbs were elevated without plaster fixation. Flexion and extension movements were conducted actively and passively on different joints at the ankle from the second day after surgery. Stitches were taken out 2 weeks after surgery. A continuative period of no weight bearing was required for 6 weeks after operations. Then patients were allowed for partial weight bearing with walker boot and crutch for a minimum of 3 months postoperatively. 19
Patient assessment
Initially, a complete history was taken, a physical examination was performed, and neurovascular status and associated injuries were assessed and recorded. The following factors were assessed after treatment: time to union and time to returning to work, time to functional recovery, physical capacity, and incidence of complications (infection, delayed union, nonunion, refracture, and posttraumatic cubometatarsal arthritis).
Functional outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) 20 mid-foot scoring system and Visual Analog Scale–Foot and Ankle (VAS-FA) score at follow-up immediately after treatment and at 6 months and 12 months after treatments. In AOFAS system, both subjective and objective clinical variables were evaluated, including pain (40 points), function (45 points), and alignment (15 points), with a maximum score of 100 points. Based on the postoperative AOFAS score, the outcome was rated as excellent (90–100 points), good (80–89 points), fair (70–79 points), or poor (<70 points). As for the VAS-FA score, the outcome was rated as 0 to 10 points, with higher scores indicating more severe pain.
Radiographs were taken immediately after surgery and at 1 month, 3 months, 6 months, and 12 months (Figure 1(c)) after treatment. The radiographs were examined for any evidence of fracture healing, implant failure, or plate migration. Radiographic healing was defined as any evidence of bridging callus across the fracture site or the obliteration of fracture line.
Statistical analysis
Statistical analysis was done using statistical software SPSS (version 20.0). Continuous variables were compared by applying Student’s t test. The p value <0.05 was considered as statistically significant.
Results
Forty-one patients were followed up for 12 months. All incisions were phase I healed without any infection. All fractures in both groups got primary union except for three patients in nonoperative group with malunion, two of whom had frequent mild to moderate plantar pain. No sural nerve injury was found in operative group.
Patients were allowed to walk with full weight 5–6 weeks postoperatively, depending on the situation of patients. Full weight bearing time was significantly different between two groups (p < 0.05, 6.62 ± 0.74 weeks in operative group and 7.42 ± 1.01 weeks in nonoperative group). When the patients had normal gait and felt no pain or just little discomfort is considered the time to return to work. Patients in the operative group could return to work significantly earlier (p < 0.05) after receiving treatment than those in nonoperative group. The time to return to work was 8.05 ± 0.87 weeks and 9.25 ± 0.97 weeks in operative and nonoperative groups, respectively.
At the follow-up of 6 and 12 months after treatment, all patients underwent the AOFAS assessment. At 6 months after treatment, patients in operative group got better scores than those in the nonoperative group (p < 0.05). The average scores were 87.33 ± 3.89 in operative group and 84.15 ± 3.75 in nonoperative group. At 12 months after treatment, there was no significant difference in AOFAS between operative group (88.10 ± 2.98) and nonoperative group (86.95 ± 3.65; p > 0.05).
Immediately after treatments and at 12 months after treatments, all patients underwent the VAS-FA assessment. VAS-FA scores showed no significant difference between the two groups immediately after treatment (p > 0.05). However, at the 12-month follow-up, the VAS-FA scores of operative group were significantly better than that of the nonoperative group (p < 0.05).
Discussion
The fifth metatarsal bone is an important component of the longitudinal and transverse arch of lateral column, which plays an important role in buffering weight bearing force and maintaining lateral arch. Under the traction of peroneus brevis, fibularis tertius, and lateral plantar fascia, it is difficult to achieve the anatomic reduction and stabilization in displaced fifth metatarsal base zone I avulsion fractures. Thus, the management of fifth metatarsal base fracture, specifically zone I fracture with mild displacement in young adults and athletes, continues to be a controversial topic. Noteworthy, despite the description by some experts that nonoperative treatment can lead to a high rate of patient satisfaction, evaluation of the postoperative outcome of nonoperative treatment is scant. 15,21
The goal of surgical fixation, especially the minimally invasive surgery, is to expedite recovery and rehabilitation and decrease the risk of complications compared with nonoperative treatment. When the foot encounters severe violence, base avulsion fracture occurs easily due to the traction of tendons and ligaments. If left untreated, they could cause severe sequelae. Inappropriate treatments may result in delayed union or nonunion (refractory pain), peripheral nerve injury during operative process, and abnormal distribution of plantar pressures, which may affect the functions of mid-foot. Patients especially young adults and athletes, are active, making necessary the integrality of the fifth metatarsal.
Although the fifth metatarsal plays an important role in mid-foot function, the management of the fifth metatarsal base fracture, specifically zone I fracture with mild displacement in young adults and athletes, continues to be a controversial topic. Heineck et al. 2 suggested that when the fragment gap was more than 2 mm and the affected articular surface was more than 30%, surgical management was indispensable. Zwitser et al. 8 also hold a similar opinion that if the fifth metatarsal base avulsion fracture was comminuted or had significant displacement (>2 mm) with or without >30% intra-articular fracture, surgical management was necessary. Operative intervention can maintain the length of the fifth metatarsal and the stabilization of the insertions of tendons and ligaments. Meanwhile, surgery can provide anatomic reduction (displacement, angulation, and rotation deformity), allowing patients for early rehabilitation exercise and reducing the incidence of complications.
In this study, therapeutic effects were compared between minimally invasive surgery and conservative management. The AOFAS and VAS-FA at 6 months after treatments were significantly better in the operative group (p < 0.05). The average time to bear full weight and to return to work was also shorter in operative group (p < 0.05). The AOFAS at 12 months after treatment and VAS-FA immediately after treatment showed no significant difference (p > 0.05). Except for three patients of malunion in nonoperative group, all patients in both groups got primary union. Two cases had frequent mild to moderate plantar pain in nonoperative group. One patient was treated with conservative method, and the other was treated with a secondary surgery.
According to the results, operative management of displaced fifth metatarsal base zone I avulsion fractures in young adults or athletes can result in better outcomes in short-term compared with conservative treatment. Although the AOFAS scores at 12 months after treatments showed no significant difference between surgical and conservative management, nonoperative management may increase the incidence of posttrauma complications including delayed union, malunion, nonunion, refracture, pain, and even malfunction of mid-foot. Besides, surgical treatment allowed patients earlier full weight bearing and return to work.
A novel minimally invasive surgical technique was introduced in this study. The point reduction clamp was used during the surgery for closed reduction and temporary fixation. With the utilization of point reduction clamp in surgery, only an incision of 1 cm could be made and a cannulated screw of 3.0 mm was tapped thereafter, which could save the blood supply of metatarsal. In addition, cannulated screw can offer certain compression between fragments to maintain anatomic reduction, all of which provided a good condition for bone union and allowed for early rehabilitation exercises.
Conclusion
In conclusion, surgical intervention is necessary for young adults or athletes with displaced (2–3 mm) fifth metatarsal base avulsion fracture. Closed reduction with percutaneous cannulated screw fixation is an effective way to treat the fifth metatarsal base avulsion fracture. It not only can lessen surgical trauma to save the blood supply of metatarsal and to avoid peripheral nerve injury but also provides rigid internal fixation.
Footnotes
Authors’ contribution
Gen-Bin Wu and Bing Li contributed equally to this study.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
This study was supported by National Natural Science Foundation of China (No. 81501931).