Repair of Acute Extensor Hallucis Longus Tendon Injuries

Abstract

Background. Extensor hallucis longus (EHL) tendon injuries may occur with lacerations sustained over the dorsum of the foot and lead to hallux dysfunction. Primary repair is performed when tendon edges are opposable; however, if a gap exists between tendon edges, then reconstruction with tendon graft or tendon transfer may be necessary to restore hallux alignment and dorsiflexion. We describe the surgical technique and report the results on a large series of patients having undergone primary repair or reconstruction of EHL tendon lacerations. Methods. We retrospectively reviewed all patients undergoing EHL tendon repair or reconstruction between January 2005 and May 2012. Information on patient demographics, mechanism of injury, time to surgery, intraoperative findings, surgical repair or reconstruction technique, and postoperative function were collected. Patients were contacted by telephone for administration of the Foot and Ankle Ability Measure (FAAM) and American Orthopaedic Foot and Ankle Society Hallux questionnaires. Results. Twenty of 23 patients undergoing EHL tendon repair or reconstruction were available for review at an average clinical follow-up of 12 months (range 3-89 months) and an average telephone follow-up of 5.1 years (range 1-10.4 years). Primary EHL repair was performed in 80% of cases, with the remaining patients undergoing reconstruction with deep tendon transfer of the extensor digitorum longus tendon from the second toe. At final follow-up, 19 of 20 patients had active hallux dorsiflexion. The average FAAM Activities of Daily Living score was 94.2% (range 58.3% to 100%) and the average FAAM Sports score was 94.2% (range 65.6% to 100%). Conclusion. Primary repair or reconstruction of EHL tendon lacerations is a reliable procedure that restores hallux alignment and function in most patients as measured by the validated FAAM questionnaire. Deep tendon transfer from the extensor digitorum longus may be performed if EHL tendon edges are not opposable thus eliminating the need for allograft reconstruction.

Levels of Evidence: Therapeutic, Level IV, Case series

Keywords

trauma soft tissue repair extensor hallucis longus tendon lacerations

“Most recent studies detailing operative management have described either primary repair or secondary reconstruction as viable options.”

Introduction

Extensor hallucis longus (EHL) tendon injuries commonly occur because of laceration sustained along the dorsum of the foot or ankle. While the true incidence of EHL tendon lacerations is unknown, the largest reported series of extremity muscle and tendon disruptions (1014 cases) found that 11% of lower extremity cases involved toe extensors.¹ Although rare, closed injuries have also been described in the setting of extreme dorsiflexion against resistance,² as attritional ruptures due to tendon degeneration from local steroid injections³ or from iatrogenic thermal injury occurring during ankle arthroscopy.⁴

There is a paucity of literature on the optimal treatment for EHL tendon lacerations. Two cases of nonoperative management resulting in recovery of toe extension are often cited as evidence that some EHL tendon lacerations may be treated without surgery.^5,6 Most recent studies detailing operative management have described either primary repair or secondary reconstruction as viable options.^5,7-10 Only one study attempted to determine objective outcomes using modern scoring systems, such as the American Orthopaedic Foot and Ankle Society (AOFAS) Hallux scale.⁷ While operative management would seem to be indicated in most patients, it is important to consider potential complications from surgery, such as painful scar formation and joint stiffness from tendon adhesions.^5,10

The purpose of this study was to report on a large case series of patients with EHL tendon lacerations, treated by 2 orthopaedic surgeons, using objective standardized outcomes to include the Foot and Ankle Ability Measures (FAAM) and AOFAS Hallux scales, including assessment of EHL function by clinical exam. We believe that most patients undergoing repair of EHL tendons regain a high level of function as measured by the FAAM Activities of Daily Living (ADL), FAAM Sports, and AOFAS Hallux scales.

Materials and Methods

Patient Selection

After institutional review board approval, we reviewed the surgical logs of 2 foot and ankle orthopaedic specialists to identify patients that had been treated surgically for EHL tendon lacerations, from January 2005 to May 2012. The clinical records were obtained and reviewed for 23 patients meeting our criteria. We abstracted demographic information, including age and gender, in addition to clinical data, including date of injury, mechanism of injury, location of laceration, date of surgery, and concomitant tendon, nerve, or blood vessel injury. The operative reports were reviewed and the following data were recorded: tendon gap (if present) and type of surgery (primary repair or reconstruction). Postoperative clinic notes were reviewed for EHL function and complications such as failure of surgical repair, surgical scar pain, stiffness, parasthesias, toe deformity, or wound healing problems were noted.

Twenty of the 23 patients were available for follow-up telephone assessment. One patient refused to participate in the study, and 2 had moved and could not be located or contacted. We felt that function was the most relevant modality to assess in quantifying success of management. As such we chose the FAAM scores, including subsets for ADL and Sports for outcomes, which have been previously validated. Although the AOFAS Hallux score has been previously used to quantify outcomes after EHL repair, it is not a validated outcome measure and requires direct clinician evaluation for reliability. For this reason, AOFAS Hallux scores were obtained in only 14 of 20 patients. Patients were additionally questioned about specific symptoms such as scar pain, parasthesias, foot or toe deformity, ability to lift the hallux off the ground while standing, need for revision surgery, and the presence or absence of wound healing issues in the postoperative period.

Surgical Repair or Reconstruction Technique

Primary repair or reconstruction of the EHL tendons was performed in the operating room with the patient in supine position. A nonsterile calf tourniquet was used. The repair was approached through a longitudinal extension of the original site of laceration. In most cases, the traumatic laceration was horizontally located, and these were extended into a “Z” incision to allow access to the tendon ends. Each end of the tendon was mobilized and freshened with sharp debridement. The ankle and hallux were then placed in neutral position and the tendon ends were reapproximated and repaired with No. 2-0 Ethibond suture in a Krakow or Kessler fashion. If tendon ends were significantly retracted, locking stitches were placed in each end and gentle, steady traction was applied to achieve apposition followed by tying of the suture ends. If EHL tendon ends could not be reapproximated, then reconstruction was performed by transferring the extensor digitorum longus (EDL) tendon of the second toe to the distal EHL tendon stump as a free tendon graft (1 case) or as a deep tendon transfer (3 cases; Figures 1 and 2). Second toe extensor function was preserved by performing tenodesis of the distal second toe EDL tendon to the adjacent third toe EDL tendon.

Postoperatively, patients were placed in a short-leg splint with hallux held in slight dorsiflexion at the metatarsophangeal and interphalangeal joints for a period of three weeks. Patients were kept non–weight bearing for the initial 3-week period to prevent potential stress of the tendon repair/reconstruction and limit postoperative edema, followed by weight bearing in a short leg cast for an additional 3 weeks. At 6 weeks, patients were transferred to a removable walker boot and enrolled in physical therapy for gait training, strengthening, and range of motion of the ankle and toes for an additional 6 weeks.

Results

The average telephone follow-up was 5 years (range 1-10.4 years) in 20 of the 23 patients available for review, with only 2 patients having less than 2-year telephone follow-up. Postoperative clinical notes were available for these same patients with an average follow-up of 12 months (range 3-89 months). One patient declined to participate in the study and 2 other patients had postoperative medical records available with an average follow-up of 3 months but were not reachable for survey and were excluded.

The average age of the patients at the time of injury was 40.1 years (range 9-65 years). The gender distribution of patients was 7 males and 13 females. There was nearly equal distribution between right- and left-sided injuries, with 57% of injuries involving the right foot. In all 20 patients, detailed information about foot laceration location was available in the medical record and classified according to Al-Qattan⁷ (Table 1). In almost all patients, the mechanism of injury involved laceration to the dorsum of the foot or ankle with a sharp or heavy object (glass, knife, mirror, metal object; Table 2). In 13 of 20 cases (65%), laceration of the EHL tendon had been missed at the time of the patient’s emergency room evaluation. In these patients, primary repair of the skin laceration was performed and these patients were subsequently referred after becoming aware that they could not extend their hallux. In the 7 cases where EHL involvement had been recognized, 2 had concomitant arterial injury that underwent surgical exploration at initial presentation. The average time from injury to surgery was 19.9 days (range 0-113 days). One of the patients had prior EHL tendon repair at another institution, which reruptured 4 weeks postrepair and was confirmed on magnetic resonance imaging.

Table 1.

Zones of Extensor Hallucis Longus (EHL) Tendon Laceration and Distribution of Injuries.

Zone	Anatomic Description	No. of Patients (%)
1	At EHL insertion	0 (0)
2	Between zones 1 and 3	1 (5)
3	Over metatarsophalangeal joint	6 (30)
4	Between zones 3 and 5	6 (30)
5	Under extensor retinaculum	7 (35)
6	Proximal to extensor retinaculum	0 (0)

Table 2.

Patient Demographics and Outcomes.

Patient	Age (Years)	Gender	Mechanism	Injury Zone	Other Injuries	Time to Surgery (Days)	Initial EHL Retraction (cm)	Surgical Procedure	FAAM ADL (%)	FAAM Sport (%)	AOFAS Hallux (Total)	Notes/Complication(s)
1	56	M	Dropped knife	3	EHB	57	5	#2 EDL transfer to EHL, proximal EHL-EDL tenodesis	100	100	90	Revision EHL reconstruction
2	24	F	Broken mirror	4	—	24	6	#2 EDL transfer to EHL, proximal EHL-EDL tenodesis	97.6	96.9	85	Hallux IP joint droop
3	28	F	Dropped knife	4	—	113	6.5	#2 EDL free tendon interposition graft to EHL	100	100	100	Hallux stiffness
4	50	F	Broken mirror	5	SPN	28	7	#2 EDL transfer to EHL proximal EHL to EDL tenodesis	100	100	100	Parasthesias in SPN distribution
5	54	F	Broken mirror	5	TA, EDL, DPN, anterior tibial artery	0	0	Primary, Krakow	100	100	90	Emergent initial surgical exploration: Anterior tibial artery ligated and tendons repaired; parasthesias in DPN distribution
6	38	F	Broken glass table	5	TA, EDL, DPN, SPN, anterior tibial artery	3	0	Primary, Krakow	97.6	95.8	83	Emergent initial surgical exploration: Anterior tibial artery ligated; wound closed. Parasthesias of SPN and DPN distribution, ankle and hallux stiffness
7	47	F	Dropped glass	5	—	3	0.5	Primary, Krakow	100	100	—	None
8	36	M	Dropped metal object	5	—	3	0.5	Primary, Krakow	100	65.6	—	None
9	17	F	Dropped glass	3	—	28	0.6	Primary, Krakow	100	100	100	None
10	9	M	Cut in bathtub	2	—	8	1	Primary, Kessler-Tajima	100	100	100	None
11	57	F	Dropped knife	3	—	9	1	Primary, Krakow	58.3	96.9	—	None
12	26	M	Dropped metal object	5	—	7	1	Primary, Krakow	100	96.9	—	None
13	36	M	Dropped glass	5	—	7	1	Primary, Krakow	97.6	96.9	—	None
14	42	F	Dropped glass	3	—	16	1.5	Primary, Krakow	82.1	100	—	None
15	42	F	Dropped glass bottle	3	DM cut, nerve	8	2	Primary, Krakow	100	100	100	Wound dehiscence, managed with wound care
16	65	F	Dropped knife	4	—	16	4	Primary, Krakow	89.5	75	88	None
17	37	M	Dropped slate	3	EHB	4	5	Primary, Krakow	100	100	100	None
18	30	F	Dropped knife	4	—	55	6	Primary, Krakow	98.8	93.8	71	None
19	51	M	Dropped glass plate	4	—	43	7	Primary, Krakow	63.1	65.6	77	None
20	57	F	Dropped glass	4	—	16	10	Primary, Krakow	100	100	100	None
	40.1 (range 9-65)	7 M; 13 F				19.9 (range 0-113)	3.3 (range 0-10)		94.2 (range 58.3-100)	94.1 (range 65.6-100)	91.7 (range 71-100)

Abbreviations: M, male; F, female; EHB, extensor hallucis brevis; EHL, extensor hallucis longus; EDL, extensor digitorum longus; SPN, superficial personal nerve; DPN, deep peroneal nerve; TA, tibialis anterior.

Concomitant tendon laceration occurred in 4 of 20 (20%) cases. In 2 of these cases, extensor hallucis brevis was the other tendon injured. In 2 other cases, both tibialis anterior and extensor digitorum longus were also injured. Concomitant nerve injury occurred in 4 of 20 (20%) cases: isolated deep peroneal nerve in 2 cases; isolated superficial peroneal nerve in 1 case, isolated dorsomedial cutaneous nerve in 1 case, and combined deep peroneal and superficial peroneal nerves in 1 case. Concomitant arterial injury occurred in 2 of 20 (10%) of cases (anterior tibial artery in both cases). In both these cases, because of profuse bleeding the patients had been taken urgently to the operating room where anterior tibial arterial injury was identified and the vessel ligated. In one of these cases, orthopaedic consultation was obtained intraoperatively and tendon repair was performed at that time. The other patient with arterial injury had been stabilized at another institution and sent for foot and ankle consultation as an outpatient.

At the time of surgery, with the foot and hallux in a neutral resting position, 18 of 20 (90%) of patients had measureable extensor hallucis longus tendon retraction. The average EHL tendon retraction encountered at the time of operation was 3.3 cm (range 0-10 cm). After tendon mobilization, in 16 of 20 (80%) cases, direct primary repair of the EHL tendon was possible. In the remaining 4 cases, the EDL to the second toe was used to transfer to the distal portion of the EHL tendon. The proximal portion of EHL was variably tenodesed to the EHB tendon or EDL tendon to the second toe. Allograft tendon was not used for any of the reconstructions.

Postoperatively, complications were observed in 3 of 20 (15%) patients. One patient had delayed wound healing managed with office-based local care and subsequently developed stiffness. Hallux stiffness was additionally seen in one other patient. One patient had late development of hallux droop at the interphalangeal joint and reports of occasional toe stubbing when ambulating without shoes but did not request a revision surgery. Additionally, 3 of the 4 patients who sustained nerve injuries at the time of their tendon lacerations complained of persistent numbness in that nerve distribution at final follow-up.

Twenty patients were successfully contacted for administration of the FAAM ADL and FAAM Sports questionnaires. The average FAAM ADL score was 94.2% (range 58.3% to 100%; Table 2) The average FAAM Sports score was 94.2% (range 65.6% to 100%). In our series, 18 of 20 (90%) patients estimated their overall level of foot function and graded their foot as “normal” or “nearly normal.” Only 2 patients graded their overall foot function as “abnormal” despite having active hallux dorsiflexion. No patients considered their foot to be “severely abnormal.”

The AOFAS Hallux score was obtainable in 14 of the 20 patients. For these patients, the average Hallux pain score was 34.3 (range 20-40) and the average Hallux function score was 42.9 (range 33-45). The average Hallux alignment score was 14.5 (range 8-15). The average total Hallux score was 91.7 out of a possible 100 points (range 71-100).

Discussion

Extensor hallucis longus tendon injuries are commonly associated with lacerations sustained to the dorsum of the foot from dropping a sharp object onto an unshod foot. Prior recommendation for consideration of nonoperative management by Griffiths⁶ was based on the experience of a single patient whose physician-rated outcome of “satisfactory” result was equivalent to 5 other patients who had undergone surgical repair. As highlighted by Kass et al,¹¹ the location of EHL tendon laceration is critical to the potential success of nonoperative management. In cases where laceration occurs distal to the extensor expansion of the EHL, hallux dorsiflexion function is preserved and nonoperative treatment should be the first line of treatment. In cases of EHL laceration proximal to the extensor expansion, surgical intervention should be considered to address the loss of interphalangeal joint extension. Recently, there has been a trend toward primary surgical repair of acute tendon injuries or surgical reconstruction if tendon retraction prevents tension-free tendon opposition^3,5,7,12; however, few studies have used patient-rated objective outcome measures to quantify function after repair.⁷

The largest previously reported case series of EHL tendon lacerations included 17 patients with industrial-related injuries, of which 15 had complete tendon disruptions that underwent primary repair and postoperative immobilization with transarticular Kirschner-wire pinning of the metatarsophalangeal joint for 6 weeks.⁷ In 2 of 17 patients, an incomplete EHL tendon laceration was found at time of surgery and patients did not have tendon repair; postoperatively, these patients were treated with early mobilization. At a final follow-up of 3 months, no patients had any wound complications and the AOFAS Hallux pain score was 40 of 40, indicating no pain. The average AOFAS Hallux function score was 42.1 (out of possible 45 points), indicating very little functional limitation.

With an average follow-up of 5 years, our patients exhibited AOFAS Hallux pain and functional scores similar to those reported by Al-Qattan,⁷ suggesting that EHL tendon repair and reconstruction has durable long-term results. In contrast to Al-Qattan, our postoperative immobilization did not involve transarticular Kirschner-wire pinning, thereby eliminating the need for pin removal in the postoperative period.

In cases where direct tension-free approximation of tendon edges is not possible, case reports have described use of interpositional grafts such as fascial lata allograft or semitendinosus autograft with good results.^4,9,12 Additionally, an EHL split tendon lengthening reinforced with dermal matrix has been described as an alternative to use of free-tissue auto- or allograft.¹³ In our series, the EHL tendon edges were unable to be reapproximated in 4 patients, despite tendon mobilization. These patients underwent local deep tendon transfer of the EDL to second toe to the distal stump of the EHL tendon. Weakness of hallux dorsiflexion occurred in 1 of these 4 patients. The perceived benefit of this procedure is the use of local autogenous tissue and avoidance of allograft tissue.

The most cited complication of EHL tendon repair is painful scar formation, which can occur in as many as 38% of patients.⁵ In our series, there were few complications. Wound complication occurred in 1 of 20 patients (5%), but this case of delayed wound healing was managed nonoperatively with wound care. Hallux stiffness was reported in 2 of 20 patients (10%) and persistent hallux droop was noted in 1 of 20 patients (5%). Parasthesias in the foot were reported in 3 of 20 patients (15%), but in all cases concomitant superficial peroneal nerve or deep peroneal nerve laceration had occurred at the time of initial injury. The patient with a concomitant dorsomedial cutaneous nerve injury did not complain about parasthesias despite no attempt at nerve repair at the time of surgery.

Limitations of this study include the retrospective design and lack of strength testing of the EHL to grade level of function at latest follow up. However, from a patient perspective only 2 of the 20 patients graded their foot as “abnormal” and only 1 of the 20 patients was noted to have drooping of the hallux at the interphalangeal joint that interfered with ambulating barefoot. Strengths of the study include the large series of patients treated with a standardized surgical protocol with identification of concomitant injuries and postoperative complications, as well as assessment of outcomes with a validated functional score, the FAAM.

Extensor hallucis longus tendon injuries are most commonly the result of a sharp object dropped onto the dorsum of the foot. Primary repair is preferable when tendon edges can be reapproximated with minimal tension on the repair. However, in cases where tendon retraction persists after tendon mobilization, local deep tendon transfer of the EDL tendon from the second toe is an effective alternative to allograft reconstruction. At an average final follow-up of 5 years, 19 of 20 patients (95%) had active hallux dorsiflexion.

Footnotes

Each author certifies that our institution has approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

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