The Journal of Foot & Ankle Surgery 54 (2015) 910–916
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Intramedullary Fixation System for the Treatment of Hammertoe Deformity Attilio Basile, MD 1, Francesco Albo, MD 2, Alessio Giai Via, MD 3 1
Department of Orthopaedics and Traumatology, Azienda Ospedaliera San Camillo-Forlanini, Rome, Italy Departmento of Orthopaedics and Traumatology, Ospedale Padre Pio, Bracciano, Italy 3 Department of Orthopaedics and Traumatology, University of Rome “Tor Vergata,” Rome, Italy 2
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Hammertoe is one of the most common foot deformities. Arthrodesis or arthroplasty of the proximal interphalangeal joint using temporary Kirschner wire fixation is the most widespread method of surgical stabilization. However, this type of fixation is associated with some potential complications that can be obviated if percutaneous fixation is avoided. The purpose of the present study was to prospectively collect clinical and radiographic outcomes of operative correction of hammertoe deformity using a permanently implanted 1piece intramedullary device. A total of 29 patients with 60 painful, rigid hammertoes were prospectively enrolled, clinically and radiographically examined, operatively treated, then followed and re-examined. The outcomes were measured in terms of the American Orthopaedic Foot and Ankle Society lesser toe and visual analog pain scores. After 18 months of follow-up, the incidence of fusion with satisfactory radiographic alignment was 85% (51 of 60 toes). One toe (1.67%) developed early postoperative implant failure because of dislocation of the device, there were no cases of infection, and the mean American Orthopaedic Foot and Ankle Society lesser toe score was 87.4 1.3 and the mean visual analog scale pain score was 1.78 0.94. Twentyfive patients (86.21%) stated that they had no symptoms in the involved toes after surgery, and 4 (13.8%) experienced occasional pain, 2 (6.9%) of whom reported limitations of recreational activities and 2 (6.9%) reported persistent swelling without activity limitations. All the patients stated that they would undergo the surgery again if they had the same preoperative condition. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: digital deformity phalanx PRO-TOEÒ surgery toe
Hammertoe (HT) is one of the most common foot deformities. It is defined as dorsiflexion of the proximal phalanx at the metatarsophalangeal joint (MTPJ) and plantarflexion of the intermediate phalanx at the proximal interphalangeal joint (PIPJ). This condition is frequently associated with other foot deformities and ranges in severity from a mild, passively correctable deformity to a rigid fixed deformity. The peak prevalence of HT deformity is reported to occur in the fourth though seventh decades (1). Although the second toe is most commonly involved (2), Ohm et al (3) reported an equal frequency of occurrence in the other lesser toes. Approximately 30% of patients with HT deformity have single toe involvement, and nearly 40% have 3 toes involved (2,4–6). The etiology of HT appears to be multifactorial, and it is not exclusively associated with isolated foot
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Attilio Basile, MD, Department of Orthopaedics and Traumatology, Azienda Ospedaliera San Camillo-Forlanini, Via Nicola Pellati 45, Roma 00149, Italy. E-mail address:
[email protected] (A. Basile).
pathologic entities; however, systemic pathologic entities, such as inflammatory arthritis, diabetes mellitus, lumbosacral disc disease, neuromuscular abnormalities, and postural deformities, can influence the development of HTs. Some investigators believe that high fashion footwear, in particular, shoes with high heels and a narrow toe box, is etiologic owing to the prevalence of HT deformity in females (7). When a HT becomes symptomatic and conservative therapies have failed, surgical intervention can be indicated. The most common surgical procedures for fixed HT deformity correction are excisional arthroplasty or arthrodesis of the PIPJ, and many different fixation methods are available for stabilization of the interphalangeal interface. Because a wide range of fixation methods have been used for PIPJ fusion, some investigators speculate that a reference standard method for fixation of the PIPJ has not yet been found (1,2,7). The aim of the present study was to prospectively evaluate the clinical and radiologic results of PIPJ fusion for the treatment of the fixed HT deformity using a 1-piece intramedullary device (PRO-TOEÒ VO Hammertoe Fixation System, Wright Medical Technology, Arlington, TN) in a selected population of patients.
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2015.04.004
A. Basile et al. / The Journal of Foot & Ankle Surgery 54 (2015) 910–916
Patients and Methods From January 2012 to June 2012, we treated 117 toes in 57 patients with clinical and radiologic evidence of a fixed HT deformity (or deformities). For the purposes of the present investigation, 35 of the 57 patients (61.4%), including 71 hammertoes, were selected for inclusion. A statistical description of these patients is listed in Table 1. The inclusion criteria for all patients enrolled in the present trial were age 18 to 75 years, no current tobacco use, no previous involvement of the ipsilateral foot and/or ankle with surgery or known trauma, no major underlying medical comorbidity (i.e., uncontrolled hypertension, previous myocardial infarction, cancer, history of stroke or transient ischemic attack, chronic obstructive lung disease, cardiac arrhythmia, morbid obesity, diabetes mellitus, peripheral vascular disease, peripheral neuropathy, lumbar disc disease, or neuromuscular abnormality), full-time occupation (i.e., working 38 hours weekly), and/or active in moderate to strenuous recreational activities (i.e., walking, jogging, golfing, tennis, bowling, weight lifting, bicycling, and other active sports). These data were abstracted from the records by 1 of us (A.G.V.), and the procedures were performed by 2 of us (A.B., F.A.). Of the 35 selected patients, 28 (80%) were female and 7 (20%) were male. Their mean age was 56 (range 18 to 75) years. All the patients reported significant and persistent pain in the deformed intermediate lesser toe (second, third, or fourth toe) and related mild to severe limitations in their daily and/or recreational activities. Both feet were affected in 22 patients (62.86%), and the deformity was unilateral in 13 (37.14%). In regard to the 71 toes in the 35 patients, 43 (60.56%) were second toes, 20 (28.17%) were third toes, and 8 (11.27%) were fourth toes. The HT deformity was associated with a number of other forefoot/hindfoot deformities: 19 with hallux valgus (33.33%), 10 with partial or complete dislocation of the lesser MTPJ with metatarsalgia (17.54%), 11 with mechanical central metatarsalgia without MTPJ dislocation (19.3%), 2 with severe hindfoot valgus deformity (3.51%), and 7 with gastrocnemius retraction (12.28%). Only 7 patients (20%) (12 toes [16.9%]) were affected by isolated HT (5 bilateral), and all displayed second toe involvement. All the associated deformities were corrected simultaneously. Ten chevron/Akin and 9 scarf/Akin osteotomies were performed for hallux valgus correction, 9 Weil osteotomies for correction of an MTPJ dislocation, 6 percutaneous distal metatarsal osteotomies (second, third, and forth metatarsals) for mechanical central metatarsalgia without a MTPJ dislocation, and 2 metatarsal head resection procedures (2-3-4-5 metatarsal heads) for severe metatarsalgia with MTPJ dislocations and intractable plantar hyperkeratosis, 2 medial displacement calcaneal osteotomies for severe hindfoot valgus, and 7 gastrocnemius recessions (Baumann procedure) for gastrocnemius retraction (equinus). The patients were clinically and radiologically assessed at baseline (preoperatively) (designated time 0 [T0]) and at 2 weeks (only for wound care), 6 weeks (T1), 6 months (T2), and 18 months (T3) postoperatively. Six patients (17.14%; 11 toes [15.49%]) were lost to follow-up, leaving 29 patients (82.86%; 60 toes [84.5%]; 40 second toes [56.34%], 15 third toes [21.13%], and 5 fourth toes [7.04%]) in the final cohort. The patients were
Table 1 Statistical description of the cohort (N ¼ 71 toes in 35 patients) Variable
Mean SD (Range) or n (%)
Age (y) Gender Male Female Side Right feet Left feet Patients with bilateral hammertoes Patients with isolated second hammertoe Toe involved Second Third Fourth Associated deformity Hallux valgus Metatarsalgia with MTPJ dislocation Metatarsalgia without MTPJ dislocation Hindfoot valgus Gastrocnemius equinus Lost to follow-up Patients Toes Toes in final analysis Second toe Third toe Fourth toe Follow-up duration
56 5.9 (18 to 75)
Abbreviation: MTPJ, metatarsophalangeal joint.
7 (20) 28 (80) 37 33 22 7
(52.86) (47.14) (62.86) (20)
43 (60.56) 20 (28.17) 8 (11.27) 19 10 11 2 7
(33.33) (17.54) (19.3) (3.51) (12.28)
6 (17.14) 11 (15.49) 40 15 5 18 mo
(56.34) (21.13) (7.04) (72 wk)
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clinically evaluated using the visual analog (VAS) pain scale score and the American Orthopaedic Foot and Ankle Society (AOFAS) lesser toe score (8,9). Radiographically, we evaluated the presence of PIPJ bony or fibrous union and toe alignment. Dorsoplantar weightbearing radiographs were obtained to assess the angular alignment of the toe using the mid-diaphyseal axes of the proximal and middle phalanges (10). Alignment was considered good if the angulation was 0 to 10 , fair if 11 to 20 , and poor if >20 . The radiographs were analyzed for implant-related bone changes, and this was performed by 1 of us (A.G.V.). We used paired Student’s t tests to determine differences in the AOFAS and VAS scores between the pre- and postoperative periods. We used Microsoft ExcelÒ for WindowsÒ XP software (Microsoft, Redmond, WA) for statistical analysis. These analyses were performed by 1 of us (A.G.V.). Surgical Procedure The patients were placed in the supine position on a well-padded operating table. All operations were performed using a lower limb regional block for anesthesia, and a pneumatic tourniquet was placed above the ipsilateral ankle. The foot and ankle were exsanguinated using an Esmarch bandage, and the tourniquet was inflated to approximately 100 mm Hg above the systolic blood pressure to provide hemostasis. The PIPJ of the affected toe was exposed using a dorsal L-shape incision, with the transverse element of the incision positioned medially at the distal end of the longitudinal component. The extensor tendon and joint capsule were excised, and the articular surfaces of the proximal and middle phalanges were exposed. The distal joint surface of the proximal phalanx was resected at the level of the metaphyseal flare, with attention given to avoid excessive shortening. The cartilage of the proximal joint surface of the middle phalanx was removed, preserving the subchondral cortical bone plate to provide a platform for fixation of the implant blade. After preparation of the articular surfaces, a 1.1-mm Kirschner wire was used to ream the center of the proximal phalanx, and a dedicated blade was used to prepare the middle phalanx. Both the Kirschner wire and the blade are provided in the surgical set that includes the implant. After preparation of the arthrodesis interface between the proximal and middle phalanges, the appropriately size implant was selected, depending on the size of the proximal phalanx, the degree of plantar angulation desired (0 or 10 ), and the quality of the bone. The screw-like threaded portion of the implant was then inserted in the predrilled hole in the proximal phalanx, after which the distal blade-like portion of the implant was inserted into the reamed canal in the middle phalanx, and the bony surfaces were compressed such that the proximal surface of the middle phalanx fit flush against the distal surface of the proximal phalanx. Finally, the implant position and the angular correction were verified by direct visualization, manipulation, and fluoroscopy using multiple views. The PIPJ capsule was then repaired, and the extensor tendon was lengthened as needed. The tourniquet was then deflated and hemostasis ensured after which the wound was closed in anatomic layers. All patients were discharged the day of surgery within 8 to 12 hours postoperatively. Immediate weightbearing as tolerated with a flat postoperative shoe was allowed (with the exception of 2 patients who had required medial displacement calcaneal osteotomy and remained non-weightbearing for 4 weeks). After 4 to 6 weeks (depending on the accessory procedures performed), the patients had progressed to a standard shoe and gradually increased their activities. Physical therapy was undertaken on an as needed basis and focused on MTPJ range of motion and edema control.
Results The outcomes are listed in Tables 2 and 3. All patients stated that pain and poor toe alignment were the contributing reasons for operative intervention, and no patient remained dissatisfied at the final follow-up examination (T3). No HT recurrences (sagittal plane) developed, no deformities in the transverse plane (medial or lateral misalignment) had developed, and no malrotation (varus or valgus) deformities had been noted (T3). We observed 1 patient (3.45%; 1 toe [1.67%]), with early failure owing to dislocation of the fixation device. Also, 20 patients (68.96%; 43 toes [71.67%]) experienced toe swelling that persisted for 6 months. Two patients (6.9%; 3 toes [5%]) showed persistent toe swelling (defined as the presence of edema at the final follow-up point [T3]). Five patients (17.24%; 9 toes [15%]) displayed a fibrous nonunion of the proximal interphalangeal fusion interface. The follow-up duration was 18 months at T3 for all patients (when the patients reached the 18-month deadline, the follow-up consultations were concluded). The mean VAS score improved from 8.7 1.21 (range 3 to 9) preoperatively to 1.78 0.94 (range 0 to 5) at the final follow-up point (T3). This difference was statistically significant (p < .05). The mean AOFAS score improved from 15.4 2.5 (range 15 to 52) to 87.4 1.3 (range 52 to 100). This difference was statistically significant (p < .05).
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Table 2 Outcomes (N ¼ 60 toes in 29 patients) Outcome
Mean SD (range) or n (%)
Misalignment Implant displacement* Patients Toes Persistent swelling Patients Toes Fibrous nonunion Patients Toes Interval to fusion (wk) Infection, wound complication Postoperative symptoms None Occasional, mild Postoperative satisfaction Complete With reservations Patient would undergo procedure again Shoe wear No restrictions Required comfort shoes Required insole Activity level No limitations Limited strenuous activity
0 1 (1.96) 1 (1.67) 2 (6.89) 3 (5) 5 (17.24) 9 (15) 6.24 1.89 (6 to 24) 0 25 (86.21) 4 (13.79) 26 (89.65) 3 (10.34) 29 (100) 25 (86.20) 2 (6.89) 2 (6.89) 27 (93.10) 2 (6.89)
* Returned to the operating room for revision surgery with Kirschner wire stabilization.
All the patients reported gradual improvement in toe symptoms throughout the observation period. We observed statistically significant improvements in toe pain between the baseline and each of the follow-up examinations (Table 3). At T0, the mean VAS pain score was 8.7 1.21, and the mean AOFAS score was 15.4 2.5 (p < .05). At T1, the mean VAS pain score was 5.3 1.1, and the mean AOFAS score was 57.9 2.4 (p < .05). At T2, the mean VAS pain score was 3.7 2.9, and the mean AOFAS score was 78.5 3.1 (p < .05). At T3, the mean VAS pain score was 1.78 0.94, and the mean AOFAS score was 87.4 1.3 (p < .05). At the final follow-up point (T3), 25 patients (86.21%; 54 toes [90%], including the toe that sustained the immediate postoperative PIPJ fusion displacement), stated that they had no lesser toe symptoms. Four patients (13.79%; 5 toes [8.3%]) experienced occasional mild lesser toe pain. Twenty-six patients (89.65%) were completely satisfied with the procedure, and 3 (10.34%) were satisfied with reservations. However, they considered the surgery successful because of the improvement from their preoperative status. In 2 patients (6.89%), the reasons for satisfaction with reservations were metatarsalgia and persistent edema in 1 and occasional toe pain in the other, who had also undergone hallux valgus correction and second metatarsal Weil osteotomy to reduce second MTPJ dislocation. All the patients stated they would undergo the lesser toe surgery again. Twenty-five patients
Table 3 Comparison of preoperative (T0) and postoperative (T3) outcome scores (N ¼ 60 toes in 29 patients) Score
Preoperative
Postoperative*
p Valuey
VAS pain AOFAS lesser toe
8.7 1.21 1.78 0.94
15.4 2.50 87.40 1.30
6 weeks. Other issues with percutaneous Kirschner wires for HT correction include the risk of trauma to the toe pulp, painful extraction, articular damage, and unnecessary arthrodesis of the distal interphalangeal joint (2,19). Furthermore, the presence of the wire need protection and care in the postoperative course, and its removal can cause anxiety and pain to the patients. Several investigators reported a nonunion rate of 20% after PIPJ arthrodesis fixed by an intramedullary Kirschner wire (7,20). The high rate of pseudoarthrosis and nonunion probably resulted from the lack of rotational control of the Kirschner wire (21). Some studies have indicated that fibrous union does not necessary lead to a greater rate of unsatisfactory clinical outcomes (2,22,23). Other investigators reported that Kirschner wire fixation can result in up to a 23% rate of sagittal plane malalignment and a 21% rate of transverse plane malalignment (10). However, to the best of our knowledge, no very long follow-up reports have been published on the outcome of fibrous union of the PIPJ after Kirschner wire fixation (1). To overcome these problems, different fixation methods have been proposed. Konkel et al (23) used absorbable pins in 33 patients (47 toes) and reported an 87% fusion rate. They found that the use of an intramedullary absorbable pin resulted in low malunion rate, few complications, and high patient satisfaction (23). Other investigators believe that absorbable fixation can be a good alternative when the patient has a metal allergy (24). However bioabsorbable pins have not been widely applied. Adverse tissue reactions, along with poor mechanical properties, have not allow the widespread use of these materials (25). Investigators have stated that absorbable fixation devices, certainly those made from polyglycolide, should not be used because of the high percentage of foreign body reaction with dissemination of the polymeric debris (26). Fusion of the PIPJ with an intramedullary cannulated screw was described by Caterini et al (1). They reported a high percentage (94%) of fusion and no recurrence of the deformity. In 13% of cases, the screws had to be removed because of breakage, infection, and pain caused by the head of the screw. In 2005, Lane et al (27) reported that digital fusion with cannulated screws was simple, reliable, and effective. Both Caterini et al (1) and Lane et al (27) stated that the advantages of this technique include the low malunion and nonunion rates owing to stable compressive fixation, the quick return to activity, and the ease of hardware removal. The disadvantages of this technique include the risk of a second operation for hardware removal and the sacrifice of the distal interphalangeal joint due to penetration of the screw. They concluded by stating that long-term follow-up studies are necessary to know the final outcome of the
distal interphalangeal joint in those patients who underwent reoperation for screw removal (1,27). Other investigators described an intraosseous loop of stainless steel wire suture to achieve stable fixation of the PIPJ arthrodesis (15). However, they did not report the number of patients treated with this technique nor the complication rate. In some cases, to achieve stable fixation, they used temporary percutaneous Kirschner wire transfixation. Recently, Catena et al (2) reported the results of a prospective study of HT correction with a 1-piece intramedullary implant (Smart ToeÒ; Stryker, Kalamazoo, MI) and a mean follow-up period of 12 months. The implant is a memory-metal device stored at cooler temperatures that, once implanted at body temperatures, expands in width (3 mm) and shortens in length (2 mm). Expansion secures the implant in place, and shortening aids in approximating the adjacent bony surfaces, with the goal of an increase in 3-plane stability and union rates. However, they used this device in conjunction with a Kirschner wire to add in the stability of the construction. The Kirschner wire was removed 3 to 4 weeks after the operative procedure. They had no recurrences of the HT deformity nor development of malalignment, and they reported a 78% of bony union rate (22% of fibrous union) (2). The percentage of bony union was almost identical to previous reported union rates using Kirschner wire fixation (9). They stated that they did not have an explanation for the 22% rate of fibrous union and that distraction of the prepared bony surfaces was not a rare finding (2). The reported satisfaction rates and pain scores (AOFAS and VAS scores) did not depend on the radiographic findings of bony versus fibrous union. They detected a 12% rate of implantrelated bone changes and a 5% rate of superficial infection (2). Witt and Hyer (21) presented the results of HT correction using the PRO-TOEÒ (PRO-TOEÒ VO Hammertoe Fixation System; Wright Medical Technology) in 3 patients (7 toes). The patients were followed up for approximately 1 year after surgery, and no intraoperative or postoperative complications were observed. The implant maintained proper clinical and radiographic alignment throughout the observation period, without implant failure or breakage. All 3 patients were satisfied with the cosmetic appearance of their surgically corrected toes and were able to perform all activities of daily living without the use of assistive devices (21). In our series, we had good clinical outcomes, and pain was significantly improved at the final follow-up visit. Twenty-five patients (54 toes) reported no limitations of their daily and athletic activities. Two patients (2 second toes) reported some limitations in their recreational activities and 2 other patients (3 toes: 2 second toes and 1 third toe) experienced persistent swelling (and some pain) of the operated toes, but this complication did not cause them any limitations if they wore comfort shoes. We detected no infection, and no patient needed hardware removal. We believe that the absence of infection and that no patient needed screw removal was because the device is completely internalized. All patients stated they would undergo the lesser toe correction procedure again. Our clinical and radiographic results are comparable to those presented by other investigators who used internal devices for PIPJ fusion (1,2,21,27). We believe that for the success of any elective orthopedic surgery, the accurate selection of the patients is extremely important. We selected a population of active, healthy, young adult patients to limit the possible complications using a relatively new fixation device. The importance of accurate patient selection in foot and ankle surgery has been underlined by various investigators (28–31). We found radiographic signs of PIPJ nonunion in 9 toes (15%), a percentage comparable to the results other studies investigating the outcomes of HT deformity correction using 1-piece intramedullary devices (screws, absorbable pins, or other devices) or Kirschner wires (1,2,7,21,23). In all cases in which nonunion occurred, we observed a
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Fig. 3. (A and B) Osteolysis of the middle phalanx.
fibrous union of the PIPJ that was sufficiently strong enough to maintain the correction (T3). From the clinical perspective (AOFAS and VAS scores), we detected no differences between the patients with bony or fibrous fusions. Other investigators have reported the same rate of satisfaction in patients with arthrodesis of the PIPJ versus patients with fibrous union (1,2,7,21,23). We detected implant-related bony changes (osteolysis of the middle phalanx) in 3 toes in which fibrous union of the interphalangeal interface was found (Fig. 3). Nonetheless, the digits remained stable and maintained alignment. It is reasonable to believe that the micromotion at the level of the implant blade caused the local osteolysis. We had 1 case of early failure of the device. It occurred in 1 of our first 5 procedures owing to a technical error. Too much subchondral bone was removed and not enough trabecular bone was left in situ for fixation of the implant blade, leading to implant dislocation from the middle phalanx. The implant was removed, and a Kirschner wire was used to fix the arthrodesis, with good clinical results at the follow-up endpoint. However, for the purposes of our study, we considered it a treatment failure. We stress the importance of maintaining the integrity of the middle phalanx subchondral plate to provide a solid platform for fixation of the implant blade. We did not observe any case of vascular impairment. This complication would require the removal of the fixation device. This operation is very simple and fast, when Kirschner wire fixation is used. With any type of intramedullary fixation, this could require an emergency open hardware removal procedure. Another problem could be the cost of the device. The present study had several limitations. First, we did not include a control group. Many different procedures are available in published studies; however, a reference standard procedure is still lacking; thus, it was difficult to compare the different techniques (1,2,7,21,23,27). The short follow-up endpoint (18 months) was another limitation; however, we preferred to not lose patients by attempting a longer follow-up period. A study with a longer follow-up duration might provide information regarding the outcomes of intramedullary implants and the bone implant interface in cases of fibrous union with
the passage of time. Another important confounding factor was that the great majority of our patients (22 of 29 [75.86%]) underwent multiple concurrent forefoot and/or hindfoot procedures that potentially could have affected the outcome of the HT correction. However, it is very common in foot and ankle daily practice to correct multiple deformities at the same surgical session. It would be very difficult to evaluate the outcomes of a single procedure in such patients. Thus, most published studies have been case series (level IV evidence), including ours. The AOFAS scoring system is not a validated instrument; however, it has been widely used in published studies, and it allowed us to compare our results with those of previous published studies. Furthermore, we acknowledge that the small sample size made statistical analysis of the data difficult and our conclusions should be taken with caution. The restrictive inclusion criteria limited the generalizability, because many patients with a wide range of systemic diseases develop symptomatic HTs. The substantial loss to follow-up, namely 6 patients (17.14%) and 11 toes (15.49%), is also a threat to the validity of our conclusions, although we believe the losses were random, excluding the fifth toe, because they were not fused. In conclusion, HT deformity correction using a specifically designed 1-piece intramedullary system is a feasible and reproducible technique in a carefully selected patient population. It will provide good alignment, substantial pain reduction, and improved function with a low complication rate. We believe it is a safe and effective procedure; however, because our investigation had several limitations, additional studies are needed.
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