Correction of Hallux Valgus Interphalangeus With an Osteotomy of the Distal End of the Proximal Phalanx (Distal Akin Osteotomy)

Introduction

Hallux valgus interphalangeus (HVI) is a deformity of the first toe resulting from lateral deviation of the distal phalanx in relation to the proximal phalanx.^2-4 As with hallux valgus, the cause of HVI is likely multifactorial. Developmental and growth plate abnormalities of the distal toe as well as pressure on the distal phalanx from shoe wear and push-off have all been suggested as causes.^2,3 HVI can occur in combination with hallux valgus, hallux rigidus, and as an isolated deformity. HVI alone is rarely symptomatic but can impinge on the second toe, contributing to second toe symptoms and deformity. HVI also contributes to the visual and radiographic alignment of the first toe for both the preoperative and postoperative assessment of hallux valgus.

Osteotomy of the proximal phalanx of the hallux has been used in the treatment of both hallux valgus and HVI. In 1925 Akin described realignment of the first toe with a medial closing wedge osteotomy at the base of the proximal phalanx. ¹ This osteotomy is still used in combination with other hallux valgus correction procedures to achieve additional correction of the alignment of the proximal phalanx and is also used for correction of HVI.^6,8 Other types of oblique osteotomies of the proximal phalanx have been described but these are mostly used as adjunct procedures for obtaining additional angular correction of a hallux valgus deformity. ⁸

The apex of the typical HVI deformity (center of rotation angle or CORA) is at the interphalangeal joint. An Akin osteotomy is done at the base of the proximal phalanx which is at the opposite end of the bone from where the HVI deformity occurs. We moved the site of the osteotomy to the distal end of the proximal phalanx and closer to the apex of the deformity. The purpose of this study was to review the results of using a distally placed medial closing wedge osteotomy in the correction of HVI.

Methods

From 2002 to 2015, an osteotomy at the distal end of the proximal phalanx was used to correct a HVI deformity in 33 patients (33 feet). The indications for this procedure were to obtain correction of the HVI in combination with a hallux valgus deformity, to correct symptomatic impingement of the first toe on the second toe, or a combination of these problems. Patient and radiographic data were recorded at the time of treatment in our surgical database and then reviewed retrospectively. Institutional review board approval was obtained.

The patients ranged in age from 16 to 80 years. There were 24 females and 9 males and 24 right feet and 9 left feet in the series. All of the patients had 1 or more other forefoot procedures performed along with an osteotomy for correction of HVI (Table 1). Six patients had an associated mild asymptomatic hallux valgus deformity that was not corrected. Eight of the 33 procedures were revisions of prior failed forefoot surgery (none of these patients had prior HVI surgery).

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Table 1.

Associated Forefoot Deformities.

Associated Forefoot Deformity	Number of Patients/Feet	Indication for Correction of Hallux Valgus Interphalangeus
	33/33
Hallux valgus	5	Improve appearance of the first toe
Hallux rigidus	3	Correct impingement on second toe
Hallux valgus and lesser toe deformities	10	Improve appearance of the first toe and correct impingement on second toe
Mild hallux valgus and lesser toe deformities—hallux valgus not corrected	6	Correct impingement on second toe “make room for second toe”
Lesser toe deformities	9	Correct impingement on second toe “make room for second toe”

HVI has been defined as having a hallux valgus interphalangeus angle (HVIA) greater than 10 degrees.^3,6,7 The HVIA was measured on weight-bearing AP radiographs by drawing a line down the central axis of the both distal and the proximal phalanx. The HVIA was the intersecting angle. The proximal phalangeal articular angle (PPAA) and distal phalangeal articular angle (DPAA) were measured by drawing a line down the center of the proximal phalanx. The intersecting articular line was drawn across the condyles of the proximal and distal end of the phalanx, respectively (Figure 1A and B).

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Figure 1.

Standing anteroposterior radiographs of the foot. The method for measuring the hallux valgus interphalangeal angle (HVIA) (A) and the distal phalangeal articular angle (DPAA) and proximal phalangeal articular angle (PPAA) (B) is shown.

All of the radiographic measurements were done by the author using the Picture Archiving and Communication System (PACS). The HVIA was the most clinically useful radiographic measurement. The preoperative, postoperative, and follow-up HVIA was measured and recorded at the time of treatment. All of the radiographs were then retrieved from the PACS archive and remeasured at the time of this review. The maximum difference in HVIA between the initial and repeat measurements was 2 degrees.

The preoperative PPAA and DPAA were recorded but were only used to confirm the observation as to whether the deformity was primarily at the proximal or distal end of the proximal phalanx. These measurements were affected by rotation of the toe and changes in the shape and orientation of the condyles after surgery (especially the DPAA) so we did not record these measurements postoperation or on rereview.

Measurements of interphalangeal (IP) joint range of motion before and after surgery were not used for assessment as there were notable differences before surgery between active and passive IP joint motion, and the accuracy of the angular measurements was also uncertain. None of the patients had symptomatic clinical or radiographic arthritis of the IP joint.

The average preoperative HVIA was 16 degrees (range 7-32 degrees, with only 3 patients having a HVIA less than 10 degrees). The average preoperative DPAA was 9 degrees (range 2-20 degrees) and the PPAA was less than 4 degrees in all 33 patients.

Operative Technique

The intent of the osteotomy was to realign the toe clinically and correct the HVIA to neutral. A dorsal midline incision was used beginning at the level of the interphalangeal joint and extended proximally about 2 cm. The fascia over the extensor hallucis longus (EHL) tendon was divided longitudinally. The EHL was retracted laterally. The periosteum was elevated from the dorsal and medial surfaces of the phalanx. The dorsal capsule of the IP joint extended proximally about 1 cm from the articular surface and was left intact. Retraction for performing the osteotomy was done with small handheld retractors, as Homan type retractors and self-retaining retractors stretch the soft tissues and block access to the bone with the oscillating saw through this small incision.

The distal limb of the osteotomy was marked along the proximal edge of the dorsal capsule about 1 cm proximal and parallel to the articular surface, leaving the lateral cortex intact. The proximal limb was marked at the desired angle of correction also leaving the lateral cortex intact (Figure 2). When making the cuts, the thickness of the saw blade should be considered and the cut should be made on or inside the planned lines to avoid removing too much bone. Observation during the course of this study showed that the length of the medial wedge can be estimated at about 3 mm per 10 degrees of desired correction.

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Figure 2.

Same radiograph as Figure 1. Position of the proximal and distal osteotomy cuts. The triangle-shaped wedge is the amount of bone to be removed.

The cortical bone at this location was thick and the working space was small, so it can be difficult to tell when the plantar cortex has been cut with the saw. To avoid injury to the FHL and the adjacent neurovascular bundles, both limbs of the osteotomy were cut (leaving the lateral cortex intact) about two-thirds of the anteroposterior diameter of the bone. This dorsal wedge-shaped fragment was removed with a small curette. The remaining wedge of medial and plantar cortex was then easy to see and the osteotomy was completed. A curette or freer was used to ensure that the wedge was properly cleared so that there would be uniform contact when the osteotomy was closed. If additional varus correction was needed, the osteotomy was held loosely closed and the oscillating saw was used to make a cut through the osteotomy site (kerf cut) for about three-fourths of the width of the bone.

Fixation was achieved with a single smooth 0.45 C wire placed through the tip of the toe, across the IP joint and osteotomy site, to the base of the proximal phalanx. Intraoperative radiographs were obtained using the mini-C arm. (Figure 3). Rotation of the distal toe could also be corrected, if needed, by cutting (or breaking) the lateral cortex but this makes the osteotomy more unstable, and fixation with 2 pins is recommended.

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Figure 3.

Fifty-five-year-old woman with hallux rigidus and hallux valgus interphalangeus causing impingement on the second toe. Correction of hallux rigidus with cheilectomy and interpositional arthroplasty. Preoperative (A) and postoperative (B) radiographs.

The fascia was approximated over the EHL and the skin was closed with nylon sutures. The pin(s) were left in place for 4 weeks and then removed in the office. The aftercare required by the associated forefoot procedures determined the weight-bearing status and the need for additional immobilization. Follow-up varied according to the associated procedures and with the time to resolution of each patient’s problems. The minimum clinical follow-up time was 4 months. Follow-up radiographs were obtained on the first postoperative visit, at 4 weeks, and then at time intervals as needed based on the associated procedures. Patients who returned during the study dates for any reason had a reevaluation of their HVI correction as well.

Results

The HVI was corrected to neutral based on clinical observation in all of the patients. The final postoperative average HVIA was 2 degrees of valgus (range 5 degrees of varus to 5 degrees of valgus) (Figure 4).

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Figure 4.

Fifty-year-old woman with metatarsalgia, hallux valgus, and hallux valgus interphalangeus (HVI) causing second toe impingement. Correction of hallux valgus with biplane chevron osteotomy; HVI with distal osteotomy; second toe metatarsalgia with second metatarsal osteotomy. Figures 1 and 2 show the preoperative radiograph. Seen for another reason at 7 years after surgery with follow-up radiograph.

The incision used for correction of the HVI healed in all of the patients and there were no postoperative infections. There were no complications related to pin fixation used for HVI correction. The osteotomy healed by both clinical examination and radiographic evaluation in 31 of 33 feet. In 2 patients, there was a persistent thin radiolucent line at the osteotomy site but no symptoms at 6 months postoperation. One patient dropped a heavy metal bar on her unprotected foot at 8 weeks postoperation and fractured the toe through the osteotomy site—this healed uneventfully although she continued to have pain and swelling for several months.

All of the patients were asked about the presence of any symptoms at the IP joint (pain, stiffness, swelling, sensitivity of the incision with shoe wear). None of the patients reported any of these problems related to the osteotomy other than a period of swelling after the surgery. After surgery, all patients had active flexion and extension of the IP joint. As all of the patients had 1 or more associated forefoot problems being surgically treated, the outcomes rating systems (specifically AOFAS) were not helpful in evaluating the effects and outcome of correcting HVI with this osteotomy.

There was one intraoperative complication. After cutting and removing the wedge, too much lateral bone was left intact and on closing the osteotomy a fracture extended distally into the IP joint. The osteotomy and fracture healed and the intra-articular step-off was not symptomatic at evaluation 1 year after surgery.

Discussion

Hallux valgus interphalangeus is a common deformity that usually is not symptomatic and requires no intervention.^3,7 Correction of larger angle HVI deformities may be considered in association with correction of hallux valgus to improve the appearance of the toe. Correction may also be considered for symptomatic impingement on the second toe. In this study, correction of HVI using an osteotomy at the distal end of the proximal phalanx was effective with few complications.

Clinical findings and symptoms were a better indicator of the need to consider operative correction of HVI than any particular radiographic parameter. The HVIA was the most useful measurement for planning the correction of the HVI because the goal was to correct the HVIA to neutral. HVI has been defined as an HVIA greater than 10 degrees but the HVIA does not necessarily correlate with symptoms. As with all foot and ankle radiographic parameters, clinical correlation is required. The 3 patients with a HVIA less than 10 degrees still had symptomatic impingement of the first and second toe and benefited from operative correction.

The DPAA and PPAA were measured and, as expected, an increased DPAA was associated with an increased HVIA. The primary use for these measurements was to confirm the location of the valgus deformity distal to the metatarsophalangeal joint. This valgus can result from a deformity of the proximal or distal phalanx; a deformity within the interphalangeal joint; a valgus alignment of articular surface of the proximal or distal end of the proximal phalanx (as measured by the DPAA and PPAA); a valgus alignment of the proximal articular surface of the distal phalanx; or a combination of deformities.

The apex of the deformity of HVI in this series was at the IP joint with an increase in both the HVIA and the DPAA. Correcting this deformity at the distal end of the phalanx resulted in removal of a smaller wedge of bone (correction closer to the CORA) than would be needed if the same deformity were corrected with an osteotomy at the proximal end of the phalanx. This distal osteotomy also corrects the HVI deformity without creating a zig-zag appearance of the toe. The joint stiffness common with a juxta-articular osteotomy may also be better tolerated at the IP joint than at the MTP joint.

If the apex of the valgus deformity were at some other level, then the site of the osteotomy could be modified to be closer to the CORA. If, for example, the valgus occurred at the base of the proximal phalanx (resulting in an increased PPAA) then a proximal phalangeal osteotomy would be preferred. If HVI is associated with symptomatic arthritis of the IP joint then correction with a realignment arthrodesis of the IP joint should be considered.

Associated hallux valgus may result in pronation of the toe, which decreases the apparent HVIA and underestimates the HVI deformity.^5,9 After correction of the hallux valgus and derotation of the toe, the HVI deformity may become more apparent both visually and radiographically. If so, intraoperative radiographs can be obtained and correction of the HVI (if needed) can be planned accordingly.

There were several limitations to this study. All of the patients had 1 or more forefoot problems that also required operative correction, including 8 patients who had a revision of prior failed forefoot surgeries. This affected the usefulness of any outcomes studies specific for the HVI correction. The follow-up was also short (minimum follow-up was 4 months) based primarily on the resolution of the patient’s other forefoot issues. As such, it is not known whether any patients over a longer time developed recurrence of their HVI or problems related to the interphalangeal joint. However, we have seen 8 of the patients back at more than 5 years postoperation for other unrelated foot problems and there has been no recurrence of HVI or IP joint symptoms in these patients.

Conclusion

Correction of an HVI deformity was achieved with an osteotomy at the distal end of the proximal phalanx. This was a safe technique with few complications and with good results in terms of both correction and patient satisfaction.