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Locking Compression Plate Distal Ulna Hook Plate as Alternative Fixation for Fifth Metatarsal Base Fracture
The Journal of Foot & Ankle Surgery xxx (2014) 1–7
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The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Original Research
Locking Compression Plate Distal Ulna Hook Plate as Alternative Fixation for Fifth Metatarsal Base Fracture Sang Ki Lee, MD 1, Ju Sang Park, MD 2, Won Sik Choy, MD 1 1 2
Professor, Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Korea Doctor, Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Korea
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Intramedullary screw fixation has been the most common treatment for fifth metatarsal base fractures. However, screw application will not achieve accurate reduction in fractures with small fragments, osteoporotic bone, or Lawrence zone 1 fractures. Because of the similar anatomic architecture between the distal ulna and the fifth metatarsal base, the purpose of the present study was to assess the results of a locking compression plate distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. A total of 19 patients with Lawrence zone 1 (n ¼ 12) or 2 (n ¼ 7) fractures of the fifth metatarsal base were treated surgically with a locking compression plate distal ulna hook plate. The patients were evaluated clinically and radiographically, and the functional outcomes were graded using the American Orthopaedic Foot and Ankle Society midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean American Orthopaedic Foot and Ankle Society midfoot score improved from 26 (range 0 to 45) points preoperatively to 94 (range 72 to 100) points at the final follow-up visit. Three patients developed post-traumatic cubometatarsal arthrosis, and 1 patient developed sural nerve neurapraxia. In our experience, the distal ulna hook plate achieved a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We suggest that the locking compression plate distal ulna hook plate should be considered as an alternative treatment of multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures. Ó 2014 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: foot Jones fracture LCP post-traumatic arthrosis screw fixation trauma
Fractures located at the metaphyseal–diaphyseal junction at the base of the fifth metatarsal were first described by Sir Robert Jones in 1902 (1). These eponymous Jones fractures are known for their prolonged healing time and risk of nonunion (2–4), because the blood supply between the base of the metatarsal and the distal diaphysis has been implicated as a “watershed area.” Also, the nutrient artery can be injured during fracture (5,6). Nevertheless, even today, no specific guidelines are available for the management of these fractures, and debate is ongoing regarding their diagnosis, classification, pathomechanics, and incidence (3,7–9). Several classification systems have been used for fifth metatarsal base fractures. First, Torg (10) classified fractures involving the proximal part of the diaphysis of the fifth metatarsal into 3 types according to the radiographic appearance and healing potential. Second, Stewart (11) introduced a classification system according to the involvement of the intra-articular surface. Finally, Lawrence and Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Sang Ki Lee, MD, Department of Orthopedic Surgery, Eulji University College of Medicine, 1306 Dunsan-dong, Seo-gu, Daejeon 302-799, Korea. E-mail address: [email protected] (S.K. Lee).
Botte (12) classified these fractures into 3 types according to the anatomic subgroup: tuberosity avulsion fractures in zone 1, fractures at the metaphyseal–diaphyseal junction (Jones fracture) in zone 2, and proximal diaphyseal stress fractures in zone 3. Although conservative care has been advocated for fifth metatarsal base fractures, a serious risk exists of delayed union, nonunion, and a long period of rehabilitation (13). Dameron (2) was the first to suggest that Jones fractures in athletes should receive different treatment considerations from those for fractures in nonathletes. Subsequently, others have reported high rates of repeat fracture and delayed union after conservative treatment in athletes (2,14). Moreover, several investigators have agreed that the current treatment recommendations should include early and aggressive surgical intervention in young, active patients (4,9). Therefore, as currently suggested, displaced (less than 2 mm) or comminuted fractures of the tuberosity and fractures that involve more than 30% of the cubometatarsal joint should be anatomically reduced and fixated (15). However, no consensus has been regarding which technique will achieve the best functional outcome. Surgical management has been described using several methods, including tension band wiring (9,16), crossed Kirschner wires (17), bone grafting (18), and plating (19). Until recently, intramedullary screw fixation with or without bone grafting, such as described by
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DeLee et al (8), was the most common surgical treatment for these fractures. These techniques have been associated with a considerable risk of complications, however, in particular, the loss of reduction, pin migration, bone graft donor site morbidity, screw breakage, hardware prominence, and cubometatarsal joint arthritis (12). Furthermore, in intramedullary fixation, it will often be difficult to achieve rigid fixation and early mobilization when the distal fragment is small or comminuted or when the bone is osteoporotic (8). Recently, the locking compression plate (LCP) distal ulna hook plate (Synthes, Oberdorf, Switzerland) was introduced for the treatment of distal ulna fractures. Angular stable fixation of the fragments, regardless of the bone quality, and a lower risk of primary and secondary loss of reduction are the advantages of using this plate. Because the fifth metatarsal base and its tuberosity have anatomic architecture similar to that of the distal ulna metaphysis and its styloid process, we proposed that the LCP distal ulna hook plate might be a compatible fixation instrument for treating fifth metatarsal base fractures. The purpose of the present prospective study was to evaluate the clinical outcomes and suitability of zone 1 or 2 fractures of the fifth metatarsal base treated with an LCP distal ulna hook plate.
incision and blunt dissection were performed with great care to avoid injury to the sural nerve and peroneus brevis tendon. The sural nerve will usually lie an average of 2 to 3 mm proximally from the fifth metatarsal tuberosity (20). The periosteum was elevated gently, exposing the fracture. The fracture was then reduced and, when necessary, held with temporary Kirschner wires. Depending on the type of fracture, an interfragmentary screw was also used, if necessary. Plate application was attempted, and the hook was covered over the fifth metatarsal tuberosity. When necessary, the plate was bent between the combi-holes to fit the shape of the metatarsal shaft. Compression force was then applied distally using a periosteal elevator as the fracture fragments were reduced to their desired alignment. The plate was fixed temporarily by inserting a screw through the most distal plate hole. Once adequate reduction had been achieved, the locking screws were placed into the diaphysis of the fifth metatarsal to secure the plate to the bone. Finally, the temporarily fixed Kirschner wire, if used, was removed. Under fluoroscopic guidance, proper positioning of the plate and the length of the screw were confirmed. If the fracture was comminuted or the bone was osteoporotic, the bone defect was filled with autologous iliac crest bone or allogeneic bone graft substitute. The wound was closed in layers, and a short leg splint was applied immediately after surgery. At 3 or 4 days after surgery, the patients were allowed non-weightbearing crutch ambulation. When the pain had subsided, range of motion exercises were initiated, and the splint was replaced with a short leg removable splint. The patient was kept nonweightbearing for 3 to 4 weeks. Gradual weightbearing was allowed until the radiographs revealed evidence of union. All patients were allowed to return to full activity when they were clinically asymptomatic and had demonstrated radiographic union.
Patients and Methods
Patients
Study Design From January 2010 to October 2011, 19 consecutive patients with zone 1 or 2 fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate (Synthes). Our institutional review board approved the study protocol and consent forms. The inclusion criteria were the diagnosis of a fifth metatarsal base fracture (zone 1 or 2), skeletal maturity, and a minimum follow-up period of 6 months. The exclusion criteria were pathologic fractures and previous surgery on the affected foot or ankle. All procedures were performed by 1 surgeon (S.K.L.).
A total of 19 patients were included in the present study, including 10 males and 9 females, with a mean age of 43 (range 18 to 69) years. The right foot was involved in 11 patients and the left foot in 8 patients. Of the 19 patients, 12 had a zone 1 fracture and 7 a zone 2 fracture. The cause of injury was a simple fall in 12, a bicycle accident in 2, a traffic accident in 3, and a fall from a height in 2 patients. No patient had an open fracture. Of the 19 patients, 16 had an isolated metatarsal fracture, 2 had a metatarsal and distal radius fracture, and 1 had a metatarsal and lateral malleolus fracture. The 3 patients with multiple fractures were treated with open reduction and internal fixation with a plate. All patients underwent surgery within 5 days of the injury using an LCP distal ulna hook plate.
Implant Design Specifics
Patient Assessment
The LCP distal ulna hook plates used in the present study were made of titanium. The plates were precontoured and anatomically fit to the fifth metatarsal base properly. The shaft of the plate has pointed hooks that will grip the tuberosity of the fifth metatarsal and act as a reference point for plate application. Intercrossing locking screws will securely hold the fifth metatarsal metaphysis. The plate also has oblong holes for 2-mm cortex screws for fifth metatarsal shaft length adjustment that can offer good stability and allow for early mobilization. Unlike conventional plates, the LCP distal ulna hook plate merges locking screw technology with conventional plating techniques to provide angular stability and compression of the fragments, regardless of the bone quality and the presence of multiple fragments (Fig. 1).
The patients were evaluated clinically and radiographically, and the mean follow-up period was 9 (range 6 to 18) months. The following factors were assessed: the interval to union, functional recovery, physical capacity, and the incidence of complications (ie, infection, delayed union, nonunion, repeat fracture, and post-traumatic cubometatarsal arthritis). The functional outcomes were graded using the American Orthopaedic Foot and Ankle Society (AOFAS) (21) midfoot scoring system. In this 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. From the postoperative AOFAS score, the outcome was rated as excellent (90 to 100), good (80 to 89), fair (70 to 79), or poor (less than 70). Radiographs were taken immediately after surgery, at 2, 4, and 6 weeks, and monthly thereafter. The radiographs were examined for any evidence of fracture healing, implant failure, and plate migration. Radiographic healing was defined as any evidence of bridging callus across the fracture sites or the obliteration of the fracture lines.
Surgical Technique Under regional anesthesia, the patient was placed in the supine position on a radiolucent operating table with the knee flexed and the legs and hips padded appropriately. The surgery was aided by the use of a thigh tourniquet. A longitudinal
Statistical Analysis Statistical analysis was performed using SPSS, version 14, software (IBM, Armonk, NY). An independent-sample Student’s t test was used to compare the preoperative and postoperative AOFAS midfoot scores. The level of significance was set at p < .05.
Results
Fig. 1. Photographs of the locking compression plate distal ulna hook plate.
Radiographic bony union was obtained in all patients at a mean of 7.4 (range 4 to 16) weeks (Fig. 2). One (5%) patient had delayed union. The definition of delayed union was a fracture that had not shown evidence of union, such as callus formation and closing of the fracture gap, by 12 weeks postoperatively (22). This patient was a 68-year-old woman with severe osteoporosis. She was treated conservatively, with an additional period of non-weightbearing and wearing a short leg splint. Subsequently, she had achieved union at 4 weeks after the diagnosis of delayed union. No cases of repeat fracture, deep infection, or vascular complications were found. One (5%) patient had mild paresthesia over the sural nerve distribution that had improved after 3 months without specific treatment.
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Fig. 2. Views of an 18-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an intra-articular and comminuted zone 1 fracture. (B) Preoperative computed tomography scan showing a comminuted zone 1 fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) The plate was removed at the patient’s request after 12 months. No associated complications occurred with implant removal.
The mean AOFAS midfoot score improved from 26 (range 0 to 45) points preoperatively to 94 (range 72 to 100) points at the final follow-up visit. This improvement was statistically significant (p < .01). The postoperative follow-up data showed an excellent outcome in 16 (84%) patients, a good outcome in 2 (10%), and a fair outcome in 1 (5%); no patient had a poor outcome. Three (16%) patients showed radiographic signs of mild degenerative changes or joint space narrowing (Fig. 3). Of these 3 patients, only 2 (10%) experienced clinical symptoms of arthrosis. These 2 symptomatic patients (1 with a good result and 1 with a fair result) had mild pain with heavy work but experienced no restrictions in their daily activities. No fixation loss, such as plate migration or implant failure, occurred. Congruent and satisfactory cubometatarsal joint surfaces (anatomic or intra-articular step-off of less than 1 mm) were present in 16 (84%) patients. Two plates were removed at the patients’ request after 9 and 12 months. No associated complications developed from implant removal. The mean interval to partial weightbearing was 3.6 (range 3 to 5) weeks, and the mean interval to full weightbearing was 6.6 (range 5 to 16) weeks. All patients returned had to their regular sports activities and daily life at a mean of 11.2 (range 9 to 19) weeks after surgery.
Discussion The results of the present study have demonstrated that good outcomes can be achieved for fifth metatarsal base fractures treated
with an LCP distal ulna hook plate. The results with this technique were comparable to those with other techniques used to treat these fractures. Several predisposing factors have been implicated in the development and pathologic features of Jones fractures. The mechanism of injury has been described as a laterally directed force on the forefoot during plantar flexion of the ankle (12). Stress will be particularly high at this metaphyseal–diaphyseal junction, in part, because of the strong attachments of the base to the cuboid and fourth metatarsal base (3). Because the fifth metatarsal has the widest range of motion of all the metatarsals, except for the base, owing to its loose ligamentous connections to the fourth metatarsal, fractures of the fifth metatarsal base will occasionally result in displacement and carry a risk of delayed union or nonunion (23). The nutrient artery terminates in the proximal diaphysis, and the metaphyseal vessels supply the tuberosity. The region at which these blood vessels converge corresponds to a region of poor fracture healing (24). In addition, hindfoot varus has been implicated in overloading the lateral column, leading to the development of the fracture and the potential for repeat fracture (25). Several investigators have also reported that malunion at the base of the fifth metatarsal will adversely affect the function of the Lisfranc joint complex, which exerts the greatest range of motion at its lateral aspect (15). Conservative care has been advocated for fifth metatarsal base fractures; however, conservative treatment carries a serious risk of delayed union or nonunion. Dameron noted that when treating these
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Fig. 3. Views of a 64-year-old female with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an osteoporotic zone 2 fracture. (B) Preoperative computed tomography scan showing a true Jones fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) Radiograph at 6 months after surgery showing complete bony union but some degree of cubometatarsal joint arthrosis with subchondral sclerosis and joint space narrowing.
fractures with elastic bandages and non-weightbearing, only 60% of fractures had healed within 1 year, and 25% went on to nonunion and eventually required bone grafting (7). Zelko et al (26) found that in an athletic population, only 2 of 15 patients treated with a walking boot had healed within 20 months or less and that treatment with strapping and orthoses or simply with rest also resulted in poor outcomes. Clapper et al (27) found that union was achieved in 18 of 25 patients at 21.2 weeks with a nonoperative protocol of 8 weeks of non-weightbearing, followed by 8 weeks in a short leg cast with weightbearing. Seven patients in their study eventually required surgical treatment. Kavanaugh et al (3) found that 66.7% of patients treated conservatively for Jones fractures had delayed union. From these results and those from other reports, surgery should be recommended for fifth metatarsal base fractures. Several surgical methods have been proposed; however, all have been associated with complications, and no consensus has been reached regarding which method will provide optimal clinical results. Intramedullary screw fixation with or without grafting has been a common surgical technique for the treatment of fifth metatarsal fractures and has been reported to produce good results (6,28). Intramedullary screw fixation has had several problems. It is technically demanding, and the screws can be broken or missed at surgery or can penetrate the distal cortex. Furthermore, discomfort caused by screw head prominence, metatarsalgia, rupture of the peroneus brevis tendon, and irritation of the sural nerve have been reported (6,28). When intramedullary screws are inserted into the medullary canal, the drilling or reaming can also cause damage to the soft tissue. When included in the procedure, bone grafting adds the problems of a longer recovery time and additional skin incision to harvest the bone graft (10).
Other techniques have had problems similar to those with intramedullary screw fixation. For example, sural nerve neurapraxia has been reported with tension band wiring (9,16). Both techniques required a more than 2-cm-long longitudinal incision that runs proximally along the axis of the fifth metatarsal diaphysis from its tuberosity, which can cause injury to the pathway of the sural nerve. In contrast, the skin incision in our technique was not extended proximally to the fifth metatarsal base tuberosity but, rather, was limited over the fracture area. Therefore, with our technique, the risk of sural nerve injury will be relatively low. The optimal surgical treatment has not yet been determined, but it should include an internal fixation device that can resist the torsion, tension, and bending of the metatarsal (23). In that sense, anatomic reduction and plate fixation with some form of locking system and some degree of compression might be a solution. Various plates have been developed to stabilize fifth metatarsal base fractures (29,30). Initially, only compression plate fixation was available, and the size of the plate was too large to securely fix the fifth metatarsal tuberosity. Recently, Carpenter and Garrett (19) introduced a modified fixation technique that used the manipulated one-third tubular plate. However, their technique also involved compressive plate fixation, which required an intraoperative bending procedure to create the anatomic curvature of the fifth metatarsal base in each case, increasing the operative time. Furthermore, the tubular plate had a sharp edge that could damage the soft tissue. No systemic study of that technique with regard to the postoperative functional and radiographic outcomes has been performed. The use of locked fixation for fifth metatarsal base fractures is an attractive method to achieve stable fixation of these often unstable,
S.K. Lee et al. / The Journal of Foot & Ankle Surgery xxx (2014) 1–7
osteoporotic, and comminuted fractures. Because of the similar anatomic architecture between the fifth metatarsal base and its tuberosity and the distal ulna, we proposed using the LCP distal ulna hook plate for open reduction and fixation of fifth metatarsal base fractures. Appropriate bending of the plate could be performed to secure fixation to the fifth metatarsal base over the tuberosity. However, only 1 case in our study required bending of the plate. Ideally, by providing stable fixation of these fractures, the rehabilitation period can be minimized, with early ambulation and the initiation of active range of motion exercises. Unlike other studies of techniques for treating fifth metatarsal base fracture, we did not apply a short leg cast or recommended immobilization after surgery. Instead, we initiated active range of motion exercises an average of 3 to 4 days after surgery. Moreover, unlike other studies, in zone 1 fractures, our technique was able to achieve excellent radiographic and clinical outcomes. Lawrence and Botte (12) defined zone 1 as tuberosity avulsion fractures; that area is inserted to the plantar aponeurosis, peroneus brevis, and peroneus tertius. Overall, the incidence of zone 1 fractures in all fifth metatarsal base fractures has been reported to be approximately 93% (31). Zone 1 fractures have an injury mechanism different from those that occur in zone 2 (true Jones fracture) (7). Therefore, a fracture in this area will continuously received traction force from around the soft tissue, which could render nonoperative treatment difficult. Furthermore, zone 1 tuberosity avulsion fractures will often have fragments that are too small to allow for stable anatomic fixation (31). Therefore, Torg (10) and Wiener et al (32) recommended such
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conservative treatment as elastic bandage application and nonweightbearing for zone 1 fractures, because they could achieve good outcomes. However, Dameron (7) advocated surgical treatment because zone 1 fractures have tended to have a high rate of delayed union or nonunion. Because no consensus has been reached regarding the optimal fixation technique for zone 1 fractures, Nunley (33) suggested an alternative method that included excision of the fragment associated with the peroneus brevis. Recently, some investigators have recommended that tension band wiring is compatible for zone 1 fractures (9). They also recognized several disadvantages of tension band wiring, including skin irritation during weightbearing, the loss of pins, and sural nerve neurapraxia (9). Although zone 1 fractures have had a high incidence rate of complications, only small systemic studies have been published, and no consensus has been reached regarding their optimal treatment. Therefore, we considered that using the LCP distal ulna hook plate could be a solution. Carpenter and Garrett (19) suggested an alternative method for fifth metatarsal base fractures using a one-third tubular plate that was manipulated to a hook type. This plate also had a pointed hook, which could grasp the fracture fragment. However, the tubular plate was too large and could not achieve adequate anatomic reduction and secure fixation. In our study, the relatively smaller size pointed hook of the LCP distal ulna hook plate could act as a buttress and have a grasping effect on the small and comminuted fragments, achieving secure fixation and preventing reduction loss (Fig. 4). Moreover, if the fracture line extends from zone 1 into zone 2, the LCP distal ulna hook plate will be
Fig. 4. Views of a 47-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an intra-articular extended zone 1 fracture. (B) Preoperative computed tomography scan showing an intra-articular zone 1 fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) Radiograph at 9 months after surgery showing complete bony union and a congruent cubometatarsal joint surface.
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Fig. 5. Views of a 48-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing intra-articular involvement and fracture lines extending into zone 2. (B) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (C) Radiograph at 6 months after surgery showing complete bony union and a congruent cubometatarsal joint surface.
able to cover both areas. Thus, it could be a solution for the extensile fifth metatarsal base fracture (Fig. 5). A variety of results and complications have been associated with other techniques. The overall complication rates have been near 0% in some studies but 40% in other studies (2,3,8,18,34). In our study, only 4 patients developed complications, including sural nerve neurapraxia in 1 and cubometatarsal joint arthrosis in 3. Considering these conditions, our results are comparable to those of other techniques. The present study had some limitations. First, ours was not a comparative study of various fixation techniques. Second, severely comminuted cases were excluded because rigid plate fixation can be difficult, and will often be unachievable in some cases. When presented with such cases, the fifth metatarsal base fracture can be excised using Nunley’s procedure (20). However, we had no experience with such cases or this method. Third, the mean follow-up duration was approximately 9 months, and radiographic changes were observed in 3 patients. Therefore, with longer follow-up, the degenerative changes might have become more significant than that reported. Moreover, within the present study, no late repeat fractures or implant failures were found. However, with longer follow-up, these complications might have occurred. Because repeat fracture is a rare occurrence, it could require an exceedingly large sample size for this complication to arise. On the basis of our experience, the LCP distal ulna hook plate fit well in the fifth metatarsal base and its tuberosity. The fixation of zone 1 or 2 fractures of the fifth metatarsal base using this plate is an acceptable and alternative method that can provide good results. Furthermore, our results have indicated that it is a safe and reliable procedure to achieve anatomic reduction and stable fixation of zone 1 tuberosity avulsion fractures.
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Original Research
Locking Compression Plate Distal Ulna Hook Plate as Alternative Fixation for Fifth Metatarsal Base Fracture Sang Ki Lee, MD 1, Ju Sang Park, MD 2, Won Sik Choy, MD 1 1 2
Professor, Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Korea Doctor, Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Korea
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Intramedullary screw fixation has been the most common treatment for fifth metatarsal base fractures. However, screw application will not achieve accurate reduction in fractures with small fragments, osteoporotic bone, or Lawrence zone 1 fractures. Because of the similar anatomic architecture between the distal ulna and the fifth metatarsal base, the purpose of the present study was to assess the results of a locking compression plate distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. A total of 19 patients with Lawrence zone 1 (n ¼ 12) or 2 (n ¼ 7) fractures of the fifth metatarsal base were treated surgically with a locking compression plate distal ulna hook plate. The patients were evaluated clinically and radiographically, and the functional outcomes were graded using the American Orthopaedic Foot and Ankle Society midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean American Orthopaedic Foot and Ankle Society midfoot score improved from 26 (range 0 to 45) points preoperatively to 94 (range 72 to 100) points at the final follow-up visit. Three patients developed post-traumatic cubometatarsal arthrosis, and 1 patient developed sural nerve neurapraxia. In our experience, the distal ulna hook plate achieved a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We suggest that the locking compression plate distal ulna hook plate should be considered as an alternative treatment of multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures. Ó 2014 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: foot Jones fracture LCP post-traumatic arthrosis screw fixation trauma
Fractures located at the metaphyseal–diaphyseal junction at the base of the fifth metatarsal were first described by Sir Robert Jones in 1902 (1). These eponymous Jones fractures are known for their prolonged healing time and risk of nonunion (2–4), because the blood supply between the base of the metatarsal and the distal diaphysis has been implicated as a “watershed area.” Also, the nutrient artery can be injured during fracture (5,6). Nevertheless, even today, no specific guidelines are available for the management of these fractures, and debate is ongoing regarding their diagnosis, classification, pathomechanics, and incidence (3,7–9). Several classification systems have been used for fifth metatarsal base fractures. First, Torg (10) classified fractures involving the proximal part of the diaphysis of the fifth metatarsal into 3 types according to the radiographic appearance and healing potential. Second, Stewart (11) introduced a classification system according to the involvement of the intra-articular surface. Finally, Lawrence and Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Sang Ki Lee, MD, Department of Orthopedic Surgery, Eulji University College of Medicine, 1306 Dunsan-dong, Seo-gu, Daejeon 302-799, Korea. E-mail address: [email protected] (S.K. Lee).
Botte (12) classified these fractures into 3 types according to the anatomic subgroup: tuberosity avulsion fractures in zone 1, fractures at the metaphyseal–diaphyseal junction (Jones fracture) in zone 2, and proximal diaphyseal stress fractures in zone 3. Although conservative care has been advocated for fifth metatarsal base fractures, a serious risk exists of delayed union, nonunion, and a long period of rehabilitation (13). Dameron (2) was the first to suggest that Jones fractures in athletes should receive different treatment considerations from those for fractures in nonathletes. Subsequently, others have reported high rates of repeat fracture and delayed union after conservative treatment in athletes (2,14). Moreover, several investigators have agreed that the current treatment recommendations should include early and aggressive surgical intervention in young, active patients (4,9). Therefore, as currently suggested, displaced (less than 2 mm) or comminuted fractures of the tuberosity and fractures that involve more than 30% of the cubometatarsal joint should be anatomically reduced and fixated (15). However, no consensus has been regarding which technique will achieve the best functional outcome. Surgical management has been described using several methods, including tension band wiring (9,16), crossed Kirschner wires (17), bone grafting (18), and plating (19). Until recently, intramedullary screw fixation with or without bone grafting, such as described by
1067-2516/$ - see front matter Ó 2014 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.02.021
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DeLee et al (8), was the most common surgical treatment for these fractures. These techniques have been associated with a considerable risk of complications, however, in particular, the loss of reduction, pin migration, bone graft donor site morbidity, screw breakage, hardware prominence, and cubometatarsal joint arthritis (12). Furthermore, in intramedullary fixation, it will often be difficult to achieve rigid fixation and early mobilization when the distal fragment is small or comminuted or when the bone is osteoporotic (8). Recently, the locking compression plate (LCP) distal ulna hook plate (Synthes, Oberdorf, Switzerland) was introduced for the treatment of distal ulna fractures. Angular stable fixation of the fragments, regardless of the bone quality, and a lower risk of primary and secondary loss of reduction are the advantages of using this plate. Because the fifth metatarsal base and its tuberosity have anatomic architecture similar to that of the distal ulna metaphysis and its styloid process, we proposed that the LCP distal ulna hook plate might be a compatible fixation instrument for treating fifth metatarsal base fractures. The purpose of the present prospective study was to evaluate the clinical outcomes and suitability of zone 1 or 2 fractures of the fifth metatarsal base treated with an LCP distal ulna hook plate.
incision and blunt dissection were performed with great care to avoid injury to the sural nerve and peroneus brevis tendon. The sural nerve will usually lie an average of 2 to 3 mm proximally from the fifth metatarsal tuberosity (20). The periosteum was elevated gently, exposing the fracture. The fracture was then reduced and, when necessary, held with temporary Kirschner wires. Depending on the type of fracture, an interfragmentary screw was also used, if necessary. Plate application was attempted, and the hook was covered over the fifth metatarsal tuberosity. When necessary, the plate was bent between the combi-holes to fit the shape of the metatarsal shaft. Compression force was then applied distally using a periosteal elevator as the fracture fragments were reduced to their desired alignment. The plate was fixed temporarily by inserting a screw through the most distal plate hole. Once adequate reduction had been achieved, the locking screws were placed into the diaphysis of the fifth metatarsal to secure the plate to the bone. Finally, the temporarily fixed Kirschner wire, if used, was removed. Under fluoroscopic guidance, proper positioning of the plate and the length of the screw were confirmed. If the fracture was comminuted or the bone was osteoporotic, the bone defect was filled with autologous iliac crest bone or allogeneic bone graft substitute. The wound was closed in layers, and a short leg splint was applied immediately after surgery. At 3 or 4 days after surgery, the patients were allowed non-weightbearing crutch ambulation. When the pain had subsided, range of motion exercises were initiated, and the splint was replaced with a short leg removable splint. The patient was kept nonweightbearing for 3 to 4 weeks. Gradual weightbearing was allowed until the radiographs revealed evidence of union. All patients were allowed to return to full activity when they were clinically asymptomatic and had demonstrated radiographic union.
Patients and Methods
Patients
Study Design From January 2010 to October 2011, 19 consecutive patients with zone 1 or 2 fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate (Synthes). Our institutional review board approved the study protocol and consent forms. The inclusion criteria were the diagnosis of a fifth metatarsal base fracture (zone 1 or 2), skeletal maturity, and a minimum follow-up period of 6 months. The exclusion criteria were pathologic fractures and previous surgery on the affected foot or ankle. All procedures were performed by 1 surgeon (S.K.L.).
A total of 19 patients were included in the present study, including 10 males and 9 females, with a mean age of 43 (range 18 to 69) years. The right foot was involved in 11 patients and the left foot in 8 patients. Of the 19 patients, 12 had a zone 1 fracture and 7 a zone 2 fracture. The cause of injury was a simple fall in 12, a bicycle accident in 2, a traffic accident in 3, and a fall from a height in 2 patients. No patient had an open fracture. Of the 19 patients, 16 had an isolated metatarsal fracture, 2 had a metatarsal and distal radius fracture, and 1 had a metatarsal and lateral malleolus fracture. The 3 patients with multiple fractures were treated with open reduction and internal fixation with a plate. All patients underwent surgery within 5 days of the injury using an LCP distal ulna hook plate.
Implant Design Specifics
Patient Assessment
The LCP distal ulna hook plates used in the present study were made of titanium. The plates were precontoured and anatomically fit to the fifth metatarsal base properly. The shaft of the plate has pointed hooks that will grip the tuberosity of the fifth metatarsal and act as a reference point for plate application. Intercrossing locking screws will securely hold the fifth metatarsal metaphysis. The plate also has oblong holes for 2-mm cortex screws for fifth metatarsal shaft length adjustment that can offer good stability and allow for early mobilization. Unlike conventional plates, the LCP distal ulna hook plate merges locking screw technology with conventional plating techniques to provide angular stability and compression of the fragments, regardless of the bone quality and the presence of multiple fragments (Fig. 1).
The patients were evaluated clinically and radiographically, and the mean follow-up period was 9 (range 6 to 18) months. The following factors were assessed: the interval to union, functional recovery, physical capacity, and the incidence of complications (ie, infection, delayed union, nonunion, repeat fracture, and post-traumatic cubometatarsal arthritis). The functional outcomes were graded using the American Orthopaedic Foot and Ankle Society (AOFAS) (21) midfoot scoring system. In this 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. From the postoperative AOFAS score, the outcome was rated as excellent (90 to 100), good (80 to 89), fair (70 to 79), or poor (less than 70). Radiographs were taken immediately after surgery, at 2, 4, and 6 weeks, and monthly thereafter. The radiographs were examined for any evidence of fracture healing, implant failure, and plate migration. Radiographic healing was defined as any evidence of bridging callus across the fracture sites or the obliteration of the fracture lines.
Surgical Technique Under regional anesthesia, the patient was placed in the supine position on a radiolucent operating table with the knee flexed and the legs and hips padded appropriately. The surgery was aided by the use of a thigh tourniquet. A longitudinal
Statistical Analysis Statistical analysis was performed using SPSS, version 14, software (IBM, Armonk, NY). An independent-sample Student’s t test was used to compare the preoperative and postoperative AOFAS midfoot scores. The level of significance was set at p < .05.
Results
Fig. 1. Photographs of the locking compression plate distal ulna hook plate.
Radiographic bony union was obtained in all patients at a mean of 7.4 (range 4 to 16) weeks (Fig. 2). One (5%) patient had delayed union. The definition of delayed union was a fracture that had not shown evidence of union, such as callus formation and closing of the fracture gap, by 12 weeks postoperatively (22). This patient was a 68-year-old woman with severe osteoporosis. She was treated conservatively, with an additional period of non-weightbearing and wearing a short leg splint. Subsequently, she had achieved union at 4 weeks after the diagnosis of delayed union. No cases of repeat fracture, deep infection, or vascular complications were found. One (5%) patient had mild paresthesia over the sural nerve distribution that had improved after 3 months without specific treatment.
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Fig. 2. Views of an 18-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an intra-articular and comminuted zone 1 fracture. (B) Preoperative computed tomography scan showing a comminuted zone 1 fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) The plate was removed at the patient’s request after 12 months. No associated complications occurred with implant removal.
The mean AOFAS midfoot score improved from 26 (range 0 to 45) points preoperatively to 94 (range 72 to 100) points at the final follow-up visit. This improvement was statistically significant (p < .01). The postoperative follow-up data showed an excellent outcome in 16 (84%) patients, a good outcome in 2 (10%), and a fair outcome in 1 (5%); no patient had a poor outcome. Three (16%) patients showed radiographic signs of mild degenerative changes or joint space narrowing (Fig. 3). Of these 3 patients, only 2 (10%) experienced clinical symptoms of arthrosis. These 2 symptomatic patients (1 with a good result and 1 with a fair result) had mild pain with heavy work but experienced no restrictions in their daily activities. No fixation loss, such as plate migration or implant failure, occurred. Congruent and satisfactory cubometatarsal joint surfaces (anatomic or intra-articular step-off of less than 1 mm) were present in 16 (84%) patients. Two plates were removed at the patients’ request after 9 and 12 months. No associated complications developed from implant removal. The mean interval to partial weightbearing was 3.6 (range 3 to 5) weeks, and the mean interval to full weightbearing was 6.6 (range 5 to 16) weeks. All patients returned had to their regular sports activities and daily life at a mean of 11.2 (range 9 to 19) weeks after surgery.
Discussion The results of the present study have demonstrated that good outcomes can be achieved for fifth metatarsal base fractures treated
with an LCP distal ulna hook plate. The results with this technique were comparable to those with other techniques used to treat these fractures. Several predisposing factors have been implicated in the development and pathologic features of Jones fractures. The mechanism of injury has been described as a laterally directed force on the forefoot during plantar flexion of the ankle (12). Stress will be particularly high at this metaphyseal–diaphyseal junction, in part, because of the strong attachments of the base to the cuboid and fourth metatarsal base (3). Because the fifth metatarsal has the widest range of motion of all the metatarsals, except for the base, owing to its loose ligamentous connections to the fourth metatarsal, fractures of the fifth metatarsal base will occasionally result in displacement and carry a risk of delayed union or nonunion (23). The nutrient artery terminates in the proximal diaphysis, and the metaphyseal vessels supply the tuberosity. The region at which these blood vessels converge corresponds to a region of poor fracture healing (24). In addition, hindfoot varus has been implicated in overloading the lateral column, leading to the development of the fracture and the potential for repeat fracture (25). Several investigators have also reported that malunion at the base of the fifth metatarsal will adversely affect the function of the Lisfranc joint complex, which exerts the greatest range of motion at its lateral aspect (15). Conservative care has been advocated for fifth metatarsal base fractures; however, conservative treatment carries a serious risk of delayed union or nonunion. Dameron noted that when treating these
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Fig. 3. Views of a 64-year-old female with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an osteoporotic zone 2 fracture. (B) Preoperative computed tomography scan showing a true Jones fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) Radiograph at 6 months after surgery showing complete bony union but some degree of cubometatarsal joint arthrosis with subchondral sclerosis and joint space narrowing.
fractures with elastic bandages and non-weightbearing, only 60% of fractures had healed within 1 year, and 25% went on to nonunion and eventually required bone grafting (7). Zelko et al (26) found that in an athletic population, only 2 of 15 patients treated with a walking boot had healed within 20 months or less and that treatment with strapping and orthoses or simply with rest also resulted in poor outcomes. Clapper et al (27) found that union was achieved in 18 of 25 patients at 21.2 weeks with a nonoperative protocol of 8 weeks of non-weightbearing, followed by 8 weeks in a short leg cast with weightbearing. Seven patients in their study eventually required surgical treatment. Kavanaugh et al (3) found that 66.7% of patients treated conservatively for Jones fractures had delayed union. From these results and those from other reports, surgery should be recommended for fifth metatarsal base fractures. Several surgical methods have been proposed; however, all have been associated with complications, and no consensus has been reached regarding which method will provide optimal clinical results. Intramedullary screw fixation with or without grafting has been a common surgical technique for the treatment of fifth metatarsal fractures and has been reported to produce good results (6,28). Intramedullary screw fixation has had several problems. It is technically demanding, and the screws can be broken or missed at surgery or can penetrate the distal cortex. Furthermore, discomfort caused by screw head prominence, metatarsalgia, rupture of the peroneus brevis tendon, and irritation of the sural nerve have been reported (6,28). When intramedullary screws are inserted into the medullary canal, the drilling or reaming can also cause damage to the soft tissue. When included in the procedure, bone grafting adds the problems of a longer recovery time and additional skin incision to harvest the bone graft (10).
Other techniques have had problems similar to those with intramedullary screw fixation. For example, sural nerve neurapraxia has been reported with tension band wiring (9,16). Both techniques required a more than 2-cm-long longitudinal incision that runs proximally along the axis of the fifth metatarsal diaphysis from its tuberosity, which can cause injury to the pathway of the sural nerve. In contrast, the skin incision in our technique was not extended proximally to the fifth metatarsal base tuberosity but, rather, was limited over the fracture area. Therefore, with our technique, the risk of sural nerve injury will be relatively low. The optimal surgical treatment has not yet been determined, but it should include an internal fixation device that can resist the torsion, tension, and bending of the metatarsal (23). In that sense, anatomic reduction and plate fixation with some form of locking system and some degree of compression might be a solution. Various plates have been developed to stabilize fifth metatarsal base fractures (29,30). Initially, only compression plate fixation was available, and the size of the plate was too large to securely fix the fifth metatarsal tuberosity. Recently, Carpenter and Garrett (19) introduced a modified fixation technique that used the manipulated one-third tubular plate. However, their technique also involved compressive plate fixation, which required an intraoperative bending procedure to create the anatomic curvature of the fifth metatarsal base in each case, increasing the operative time. Furthermore, the tubular plate had a sharp edge that could damage the soft tissue. No systemic study of that technique with regard to the postoperative functional and radiographic outcomes has been performed. The use of locked fixation for fifth metatarsal base fractures is an attractive method to achieve stable fixation of these often unstable,
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osteoporotic, and comminuted fractures. Because of the similar anatomic architecture between the fifth metatarsal base and its tuberosity and the distal ulna, we proposed using the LCP distal ulna hook plate for open reduction and fixation of fifth metatarsal base fractures. Appropriate bending of the plate could be performed to secure fixation to the fifth metatarsal base over the tuberosity. However, only 1 case in our study required bending of the plate. Ideally, by providing stable fixation of these fractures, the rehabilitation period can be minimized, with early ambulation and the initiation of active range of motion exercises. Unlike other studies of techniques for treating fifth metatarsal base fracture, we did not apply a short leg cast or recommended immobilization after surgery. Instead, we initiated active range of motion exercises an average of 3 to 4 days after surgery. Moreover, unlike other studies, in zone 1 fractures, our technique was able to achieve excellent radiographic and clinical outcomes. Lawrence and Botte (12) defined zone 1 as tuberosity avulsion fractures; that area is inserted to the plantar aponeurosis, peroneus brevis, and peroneus tertius. Overall, the incidence of zone 1 fractures in all fifth metatarsal base fractures has been reported to be approximately 93% (31). Zone 1 fractures have an injury mechanism different from those that occur in zone 2 (true Jones fracture) (7). Therefore, a fracture in this area will continuously received traction force from around the soft tissue, which could render nonoperative treatment difficult. Furthermore, zone 1 tuberosity avulsion fractures will often have fragments that are too small to allow for stable anatomic fixation (31). Therefore, Torg (10) and Wiener et al (32) recommended such
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conservative treatment as elastic bandage application and nonweightbearing for zone 1 fractures, because they could achieve good outcomes. However, Dameron (7) advocated surgical treatment because zone 1 fractures have tended to have a high rate of delayed union or nonunion. Because no consensus has been reached regarding the optimal fixation technique for zone 1 fractures, Nunley (33) suggested an alternative method that included excision of the fragment associated with the peroneus brevis. Recently, some investigators have recommended that tension band wiring is compatible for zone 1 fractures (9). They also recognized several disadvantages of tension band wiring, including skin irritation during weightbearing, the loss of pins, and sural nerve neurapraxia (9). Although zone 1 fractures have had a high incidence rate of complications, only small systemic studies have been published, and no consensus has been reached regarding their optimal treatment. Therefore, we considered that using the LCP distal ulna hook plate could be a solution. Carpenter and Garrett (19) suggested an alternative method for fifth metatarsal base fractures using a one-third tubular plate that was manipulated to a hook type. This plate also had a pointed hook, which could grasp the fracture fragment. However, the tubular plate was too large and could not achieve adequate anatomic reduction and secure fixation. In our study, the relatively smaller size pointed hook of the LCP distal ulna hook plate could act as a buttress and have a grasping effect on the small and comminuted fragments, achieving secure fixation and preventing reduction loss (Fig. 4). Moreover, if the fracture line extends from zone 1 into zone 2, the LCP distal ulna hook plate will be
Fig. 4. Views of a 47-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing an intra-articular extended zone 1 fracture. (B) Preoperative computed tomography scan showing an intra-articular zone 1 fracture. (C) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (D) Radiograph at 9 months after surgery showing complete bony union and a congruent cubometatarsal joint surface.
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Fig. 5. Views of a 48-year-old male with a fifth metatarsal base fracture. (A) Preoperative radiograph showing intra-articular involvement and fracture lines extending into zone 2. (B) Radiograph after surgery showing satisfactory fracture reduction and internal fixation. (C) Radiograph at 6 months after surgery showing complete bony union and a congruent cubometatarsal joint surface.
able to cover both areas. Thus, it could be a solution for the extensile fifth metatarsal base fracture (Fig. 5). A variety of results and complications have been associated with other techniques. The overall complication rates have been near 0% in some studies but 40% in other studies (2,3,8,18,34). In our study, only 4 patients developed complications, including sural nerve neurapraxia in 1 and cubometatarsal joint arthrosis in 3. Considering these conditions, our results are comparable to those of other techniques. The present study had some limitations. First, ours was not a comparative study of various fixation techniques. Second, severely comminuted cases were excluded because rigid plate fixation can be difficult, and will often be unachievable in some cases. When presented with such cases, the fifth metatarsal base fracture can be excised using Nunley’s procedure (20). However, we had no experience with such cases or this method. Third, the mean follow-up duration was approximately 9 months, and radiographic changes were observed in 3 patients. Therefore, with longer follow-up, the degenerative changes might have become more significant than that reported. Moreover, within the present study, no late repeat fractures or implant failures were found. However, with longer follow-up, these complications might have occurred. Because repeat fracture is a rare occurrence, it could require an exceedingly large sample size for this complication to arise. On the basis of our experience, the LCP distal ulna hook plate fit well in the fifth metatarsal base and its tuberosity. The fixation of zone 1 or 2 fractures of the fifth metatarsal base using this plate is an acceptable and alternative method that can provide good results. Furthermore, our results have indicated that it is a safe and reliable procedure to achieve anatomic reduction and stable fixation of zone 1 tuberosity avulsion fractures.
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