Chronic diabetic ulcers under the first metatarsal head treated by staged tendon balancing

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1 Chronic diabetic ulcers under the first metatarsal head treated by staged tendon balancing A PROSPECTIVE COHORT STUDY R. Dayer, M. Assal From University of Geneva Hospitals, Geneva, Switzerland We studied a cohort of 26 diabetic patients with chronic ulceration under the first metatarsal head treated by a modified Jones extensor hallucis longus and a flexor hallucis longus transfer. If the first metatarsal was still plantar flexed following these two transfers, a peroneus longus to the peroneus brevis tendon transfer was also performed. Finally, if ankle dorsiflexion was < 5 with the knee extended, a Strayer-type gastrocnemius recession was performed. The mean duration of chronic ulceration despite a minimum of six months conservative care was 16.2 months (6 to 31). A total of 23 of the 26 patients were available for follow-up at a mean of 39.6 months (12 to 61) after surgery. All except one achieved complete ulcer healing at a mean of 4.4 weeks (2 to 8) after surgery, and there was no recurrence of ulceration under the first metatarsal. We believe that tendon balancing using modified Jones extensor hallucis longus and flexor hallucis longus transfers, associated in selected cases with a peroneus longus to brevis transfer and/or Strayer procedure, can promote rapid and sustained healing of chronic diabetic ulcers under the first metatarsal head.! R. Dayer, MD, Orthopaedic Chief Resident! M. Assal, MD, Orthopaedic Lecturer Department of Orthopaedics University of Geneva Hospitals, 24 rue Micheli-du-Crest, 1211 Geneva 14, Switzerland. Correspondence should be sent to Dr R. Dayer; romain.dayer@hcuge.ch 2009 British Editorial Society of Bone and Joint Surgery doi: / x.91b $2.00 J Bone Joint Surg [Br] 2009;91-B: Received 28 July 2008; Accepted after revision 15 January 2009 Ulceration of the plantar aspect of the foot in the diabetic patient is a challenging problem 1,2 and is the most common cause of lower limb amputation in diabetics in the United States. 3,4 High plantar pressure is an important factor in this type of ulceration as well as diabetic neuropathy and peripheral vascular disease. 5,6 Most diabetic foot ulcers will heal with appropriate local treatment and shoe modification, but a small number of patients have chronic ulceration despite prolonged treatment, and even when primary healing occurs a proportion recur. 7 Surgical tendon balancing procedures to reduce abnormal plantar pressure at the site of the ulcer can be used to improve healing and reduce the risk of recurrence. 8 Two retrospective studies have reported encouraging results of tendon lengthening, either alone or in combination with bone resection for chronic neuropathic plantar forefoot ulceration. 9,10 Ulceration over the prominent first metatarsal head is a frequent problem Increased pressure under the first metatarsal head is thought to result from an imbalance of the three extrinsic muscles to the first ray, extensor hallucis longus (EHL), flexor hallucis longus (FHL) and peroneus longus and intrinsic muscle weakness. 15,16 A cadaver study 16 showed that overaction of the EHL raised the pressure under the first metatarsal head. Subsequent treatment by the modified Jones procedure 17 transfer of the EHL tendon to the first metatarsal neck, with fusion of the interphalangeal joint markedly reduced the pressure in this region. 18 Transfer of the FHL from the distal phalanx of the great toe to the base of the proximal phalanx produced similar results. 18 The modified Jones procedure 17 has been reported primarily for the treatment of pes cavus with clawing of the big toe secondary to poliomyelitis and other neurological conditions, or as an idiopathic condition in children and young adults We studied the effect of staged tendon balancing using the modified Jones procedure combined with transfer of the FHL in the treatment of chronic neuropathic ulcers under the first metatarsal head in diabetic patients. Patients and Methods Between January 2002 and February 2007, 26 diabetic patients (16 women, ten men) who had failed conservative treatment for neuropathic ulceration under the first metatarsal head were enrolled in a prospective cohort study at our institution. The primary outcome measures were the time to healing of the ulcer and the rate of recurrence. The study was VOL. 91-B, No. 4, APRIL

2 488 R. DAYER, M. ASSAL Fig. 1 Photograph of a non-healing plantar ulcer under the left first metatarsal head of a 49-year-old patient with a 22-year history of type 1 diabetes. The ulcer appeared 14 months earlier and had been under treatment three times a week since then. Inspection revealed an ulcer without local signs of infection and a prominent first metatarsal with clawing of the hallux. approved by the institutional ethics committee. In cooperation with our diabetologist, glycemic control was optimised as soon as the patients entered the conservative phase of ulcer treatment. The inclusion criteria for the study were the presence of a unilateral chronic ulcer under the first metatarsal head (Fig. 1) (a chronic ulcer was defined as one that failed to heal after a minimum of six months treatment by a team specifically trained in foot care, with at least two ulcer dressing changes per week and habitual use of specific extra-depth shoes with a customised insole having a void under the first metatarsal head to reduce local pressure), diabetes, and no medical contraindications to anaesthesia. Exclusion criteria included the presence of plantar ulcers not located under the first metatarsal head, bilateral foot ulceration (we did not include bilateral ulceration because of the possible effects this might have on weight-bearing pressures, for example a patient who was operated upon bilaterally would probably be less able to walk during the first post-operative weeks, and this could be a confounding factor to ulcer healing), peripheral vascular disease associated with a transcutaneous oxygen tension (TcPO 2 ) on the dorsum of the foot < 25 mmhg, active infection as determined by abnormal blood studies (C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and blood cell count) or local signs of infection, such as cellulitis or suppuration, a prior history of ipsilateral partial foot amputation, inability to comply with follow-up, and medical contraindications to surgery and/or anaesthesia. Patients were considered to have peripheral neuropathy if they were unable to feel the touch of a 5.07/10-gauge nylon monofilament at four of ten sites on the plantar aspect of the foot, which is a validated test for the detection of a foot at risk of neuropathic ulceration due to loss of protective sensation. 23,24 Patient demographics are presented in Table I. The mean TcPO 2 on the dorsum of the involved foot was 43.8 mmhg (31 to 55). The mean duration of a chronic non-healing ulcer despite appropriate conservative treatment was 16.2 months (6 to 31), and the mean pre-operative ulcer size was 2.0 cm (1.0 to 3.5) for the greatest diameter and 1.7 cm (0.5 to 3.0) for the smallest. According to the modified Wagner-Meggitt depth-ischaemia classification described by Brodsky, 25 there were 12 patients with grade 1A ulceration and 14 with 2A (depth classification: grade 1, superficial ulceration, not infected; grade 2, deep ulceration exposing a tendon or joint (with or without superficial infection); and ischaemia classification: A, not ischaemic). Because of our exclusion criteria, there were no 2A ulcers with an associated infection or with joint exposure, which implies complete loss of the flexor tendons under the first metatarsal head, making FHL transfer impossible. The mean age at the time of surgery was 56.2 years (29 to 80). Operative technique. A single pre-operative dose of intravenous prophylactic antibiotic (cefuroxime 1.5 g) was administered one hour prior to operation. A 3 cm incision was made on the distal and dorsal aspects of the first metatarsal (Fig 2). A modified Jones EHL transfer was performed and the freed distal tendon of EHL was attached to the dorsal aspect of the neck of the first metatarsal under slight tension, using a fully threaded 2.8 mm diameter titanium suture anchor and a no. 2 polyester suture (FASTaK II Suture Anchor and no. 2 FiberWire; Arthrex Swiss Ltd, St Gall, Switzerland). Arthrodesis of the interphalangeal joint in the neutral position was then performed by excising the articular cartilage through an L-shaped dorsal incision (Fig. 2b) and fixed with a 3.5 mm cortical screw passing from distal to proximal through a 5 mm horizontal incision at the tip of the first toe. The FHL transfer was performed through a 2 cm incision on the medial aspect of the proximal phalanx (Fig. 3a). The tendon was transected at its attachment to the distal phalanx and fixed under the base of the proximal phalanx using the same type of titanium anchor and polyester suture. Traditional methods of fixation involve suturing the tendon to itself after passing it through a tunnel drilled in the bone. Biomechanical studies in cadaver models have shown that suture anchors have similar or superior mechanical properties to bone tunnels If the first metatarsal was still plantar flexed following these two procedures, a peroneus longus to peroneus brevis THE JOURNAL OF BONE AND JOINT SURGERY

3 CHRONIC DIABETIC ULCERS UNDER THE FIRST METATARSAL HEAD TREATED BY STAGED TENDON BALANCING 489 Table I. Demographic and clinical characteristics of the study population according to the surgical procedures performed. Values are means (SEM) Group * I II III Surgical procedures Number (total: 26) Women/men (total: 16/10) 11/8 3/2 2/0 Age at surgery (yrs) (3.01) (4.39) (16.00) Diabetes therapy Oral/insulin 6/13 3/2 2/0 TcPO 2 at the dorsum of the foot (mmhg) (1.97) (3.14) (2.00) Peripheral neuropathy Duration of non-healing ulcer (mths) (1.85) (2.67) (0.50) Ulcer diameter (cm) Maximum 2.05 (0.18) 1.90 (0.10) 2.00 (0.50) Minimum 1.63 (0.13) 1.90 (0.10) 1.75 (0.75) Ulcer grade (Brodsky s depth-ischaemia classification) 1A A Length of post-operative follow-up (mths) (2.44) (7.23) 48 Lost to follow-up Died during follow-up Time to healing (wks) 4.47 (0.44) 4.50 (0.87) 3.00 Failure to heal Ulcer recurrence Under the first metatarsal Other sites * surgical procedures: 1) Jones extensor hallucis longus transfer and flexor hallucis longus transfer; 2) peroneus longus to peroneus brevis transfer; 3) Strayer-type gastrocnemius recession TcPO 2, transcutaneous oxygen tension tendon transfer was performed to reduce plantar flexion of the first ray. 29,30 Through a 5 cm incision proximal to the tip of the lateral malleolus (Fig. 3b), the peroneus longus tendon was divided and sutured to the peroneus brevis tendon 31 with no. 1 resorbable polyglactic suture (Vicryl; Ethicon, Spreintenbach, Switzerland). The rationale for the procedure is based on biomechanical studies 16,18 which have shown that the peroneus longus muscle is a major contributor to increased plantar pressure beneath the first metatarsal. Finally, if ankle dorsiflexion was < 5 with the knee in full extension, 32 a Strayer-type gastrocnemius recession 33 was performed via a 5 cm posteromedial incision centred on the gastrocnemius indentation. An equinus deformity due to a gastrocnemius contracture is believed to be a potential cause of ulceration of the plantar aspect of the foot. 8,34,35 Gastrocnemius recession is a well-documented procedure for the treatment of this condition At the end of the operation, the ulcer under the first metatarsal head was carefully debrided and left open. The four procedures (modified Jones procedure, FHL tendon transfer, peroneus longus tendon transfer and Strayer procedure; group I) were used in 19 of the 26 patients. Five were managed by a modified Jones procedure, FHL transfer and gastrocnemius lengthening alone (group II). Finally, two patients were treated with the two former procedures and peroneus longus transfer alone (group III). Post-operative care and follow-up. The sutures were removed after three weeks. The foot was protected in an ankle-foot orthosis for six weeks and patients allowed to bear weight as tolerated. Wet-to-dry dressings were applied twice weekly until full epithelialisation of the ulcer had occurred (Fig. 4), when it was considered healed. The patients were then followed up at monthly intervals. Results The mean follow-up was 39.6 months (12 to 61). Two patients were lost to follow-up, and one died three weeks after surgery from a myocardial infarction, without any healing of the lesion. There was no wound infection or wound breakdown. Of the remaining 23 patients, all except one achieved complete healing of the ulcer, with no recurrence under the first metatarsal head. The mean time to healing of the ulcer was 4.4 weeks (2 to 8). In group II, the ulcer VOL. 91-B, No. 4, APRIL 2009

4 490 R. DAYER, M. ASSAL Fig. 2a Fig. 2b Fig. 2c Photographs showing a) a section of the extensor hallucis longus tendon before its transfer through a 3 cm dorsal incision on the distal aspect of the first metatarsal, b) the interphalangeal joint arthrodesis was made through an L-shaped dorsal incision and c) the forefoot after closure of the incisions for the modified Jones procedure and the flexor hallucis longus transfer. in a 70-year-old man failed to heal and required an extension osteotomy of the first metatarsal and a peroneus longus to brevis transfer six months later. Subsequent healing occurred eight weeks post-operatively. Finally, another patient in group II presented one year after surgery with ulceration under the second metatarsal head of the same foot. Discussion The presence of a chronic non-healing ulcer in a diabetic patient without peripheral vascular disease after adequate conservative treatment, including local and general medical care, should alert the clinician to an underlying anatomical abnormality causing increased local pressure. Such an ulcer under the first metatarsal head may be due to muscular imbalance between the extrinsic and intrinsic muscles of the first ray, causing an elevation of plantar pressure. 15,16 In this study we have shown that tendon balancing procedures aimed at diminishing the plantar pressure can promote rapid healing under these circumstances. The mean time to healing was 4.4 weeks after surgery, compared with a mean pre-operative duration of conservative treatment without healing of 16.2 months. The plantar ulcer failed to heal after surgery in only one of the 26 patients included in the study. There was no recurrence of ulceration under the first metatarsal head during a mean post-operative followup of 39.6 months. It could be suggested that amputation of the first ray would be a more definitive surgical solution but this pro- THE JOURNAL OF BONE AND JOINT SURGERY

5 CHRONIC DIABETIC ULCERS UNDER THE FIRST METATARSAL HEAD TREATED BY STAGED TENDON BALANCING 491 Fig. 3a Fig. 3b Photographs showing a) the location of the flexor hallucis longus tendon before its section and transfer through a 2 cm incision on the medial aspect of the proximal phalanx and b) the division and suture of the peroneus longus tendon to the peroneus brevis tendon through an incision 5 cm proximal to the tip of the lateral malleolus. Fig. 4 Photograph showing the left foot of the same patient as in figure 1 five weeks after extensor hallucis longus and flexor hallucis longus transfers, peroneus longus to peroneus brevis transfer and gastrocnemius recession. Inspection now reveals a healed planter ulcer (i.e. fully epithelialised), a less prominent metatarsal head, and disappearance of the clawing of the first toe. cedure is associated with high rates of re-ulceration and reamputation, ranging between 12.4% and 60% Other non-surgical forms of treatment for chronic plantar ulcers include negative-pressure wound therapy and offloading foot modalities such as total-contact casts, removable cast walkers or half-shoes. Negative pressure therapy seems to promote healing in a higher proportion of large diabetic foot wounds, with faster healing rates than standard moist dressings. 43,44 Although ulcer recurrence rates following this type of treatment have not been described, they could be expected to be relatively high in patients with neuropathic forefoot ulcers and increased plantar pressure. Our patients were not treated with total-contact cast during the conservative treatment phase, but with frequent ulcer dressing and extra-deep diabetic shoes, including a customised insole with a void under the first metatarsal head. This can be seen as a weakness of our study, because a totalcontact cast appears to be the most efficient way of reducing local pressure. 45 However, high recurrence rates have been reported following discontinuation of treatment with a totalcontact cast both in a prospective trial (59% in the first seven months and 81% at two years follow-up) 46 and in a retrospective study (63%). 47 The costs and complication rates associated with such treatment can be high For these reasons we agree with Laborde s 10 opinion that to consider total-contact cast as the gold standard treatment is questionable. It is obvious that in the presence of abnormal forefoot pressure associated with structural change, every offloading modality will have only a temporary effect on healing, and a high risk of re-ulceration when discontinued. The ankle-foot orthosis used during post-operative care could theoretically contribute to ulcer healing. However, it was not an off-loading modality and did not function on the principle of a total-contact cast. It did not include a halfshoe, and was not patellar tendon bearing. It was a simple removable orthosis with no pressure-relief insert, and our patients were allowed to bear weight with it as tolerated. Therefore, its contribution to healing was probably very limited. Our results with respect to ulcer healing and recurrence following tendon balancing are superior to those VOL. 91-B, No. 4, APRIL 2009

6 492 R. DAYER, M. ASSAL published with the use of total-contact cast or any other orthotic system. These findings are consistent with those of a retrospective study and a randomised clinical trial comparing the outcomes of diabetic patients with neuropathic plantar forefoot ulcer treated with total-contact cast alone or combined with lengthening of tendo-achillis. 35,46 The only patient in our cohort whose ulcer did heal following surgery was initially treated by a Jones procedure, FHL tendon transfer and gastrocnemius lengthening. A peroneus longus transfer was not performed. The poor result in this patient may have been due to intra-operative underestimation of the residual plantar flexion of the first metatarsal after the Jones and FHL transfers. Intraoperative clinical evaluation of persistent first metatarsal flexion is difficult and instruments designed precisely to assess this parameter are not available. A recent retrospective study by Laborde 10 including 13 plantar ulcers under the first metatarsal head, secondary to a variety of neuropathies (diabetes mellitus, alcoholism and lumbar radiculopathy), reported good results with peroneus longus (Z-type) lengthening in addition to gastrocnemius-soleus lengthening (Vulpuis technique). It is not yet clear which technique is preferable for the peroneus longus tendon, as tendon lengthening or transfer to the peroneus brevis have not been compared with each other, in either biomechanical or clinical studies. To our knowledge, the study by Laborde 10 is the only one to report the results of peroneus longus tendon lengthening for the treatment of diabetic ulcers. We consider that the choice of technique (lengthening or transfer to the peroneus brevis) should be left to the discretion of the surgeon. Another important consideration when comparing our work with the study of Laborde 10 is the concept of staged treatment. He treated all patients presenting with a chronic non-healing ulcer under the first metatarsal head with gastrocnemius-soleus recession and peroneus longus lengthening. Such standardised treatment does not take into account the degree of forefoot deformity. Our concept was to unload the first metatarsal by a staged protocol according to the degree of deformity of the first ray and presence of an equinus contracture, and to limit the risk of overcorrection and the potential development of a transfer lesion under the lesser metatarsal heads. Procedures that use peroneus longus tendon transfer in the treatment of clawed hallux have been shown to be associated with overcorrection. 15 For this reason, peroneus longus transfer was performed last in our staged protocol. However, one of our patients treated by Jones, FHL transfer and a Strayer-type gastrocnemius recession (i.e., procedures implying a less powerful correction of the abnormal first metatarsal plantar flexion) developed a transfer lesion under the second metatarsal head. All the patients in our study presented with a peripheral neuropathy, as determined by the Semmes-Weinstein test. The vast majority (24 of 26) also had an equinus contracture, which was the indication for the Strayer procedure in our protocol. This could corroborate with one histological study 50 in diabetic patients with neuropathy that demonstrated structural changes in the tendo-achillis compared with non-diabetic individuals, possibly resulting from nonenzymatic glycation expressed over many years. These structural changes could contribute to a tightening of the tendo- Achillis tendon-gastrocnemius-soleus complex, which is common in advanced diabetic neuropathy. However, there is increasing evidence that tendo-achillis tendon lengthening alone is probably not sufficient to prevent recurrence of forefoot ulceration. Two clinical biomechanical studies have shown that the range of movement of the ankle accounts for only a small proportion of forefoot plantar pressure in both diabetic patients and asymptomatic subjects. 51,52 Lengthening of the tendo-achillis has been shown initially to reduce plantar pressure by 27%, but it returned to very high values after eight months and persisted thereafter. 53 Based on these reports we only used tendo-achillis lengthening in selected patients at the end of our staged protocol. We believe this to be the first study to demonstrate that first ray tendon balancing by the Jones procedure and FHL transfer, associated with peroneus longus to peroneus brevis transfer and/or gastrocnemius recession in the case of persistent first ray flexion and/or equinus contracture, can successfully promote rapid ulcer healing in diabetics with chronic ulceration under the first metatarsal head. All but one of the 23 patients who completed follow-up healed their ulcer, and there was no recurrent ulceration under the first metatarsal head during a mean follow-up of 39.6 months (12 to 61). We emphasise that these findings are applicable only to a specific subset of chronic plantar ulcers in diabetic patients which have failed to respond to at least six months of conservative treatment. We are grateful to C. Poncet for his help with data collection. 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