Talonavicular joint arthrodesis and evans calcaneal osteotomy for treatment of posterior tibial tendon dysfunction

Talonavicular Joint Arthrodesis and Evans Calcaneal Osteotomy for Treatment of Posterior Tibial Tendon Dysfunction Charles M. Lombardi, DPM, Lester N. Dennis, DPM, Fiona G. Connolly, DPM, and Alison D. Silhanek, DPM The purpose of this study was to evaluate the combination of talonavicular fusion and Evans calcaneal osteotomy for the treatment of posterior tibial tendon dysfunction. This was a retrospective study of 10 patients, mean age 48.7 years, who had continued pain despite 6 months of conservative treatment and a minimum Johnson and Strom stage II deformity. Patients completed a detailed questionnaire, were physically examined, and their postoperative improvement was graded according to the American Orthopedic Foot and Ankle Society Ankle-Hindfoot Rating Scale. At a mean of 35 months (range 8 - 72 months) after surgery, patients demonstrated a significant improvement (p < .001) both in their subjective discomfort and in the structural alignment and funct ion of their feet. The authors feel that this combination of procedures allows greater correction and stability than either procedure performed alone, and provides a viable alternative to triple arthrodesis. (The Journal of Foot & Ankle Surgery 38(2):116-122, 1999) Key words: arthrodesis, calcaneal osteotomy, tibialis posterior tendinitis

P osterior tibial tendon dysfunction (PITD) and the resultant adult acquired flatfoot deformity have recently been the focus of numerous research studies. However, despite our increased understanding of this condition, its diagnosis continues to evoke the controversial question of effective treatment. With an armamentarium of procedures ranging from soft-tissue reconstruction to calcaneal osteotomies to arthrode ses, the surgeon must choose a regimen that will alleviate the patient's pain and recreate a stable, plantigrade foot. A review of the biomechanic s and deforming forces of this condition can assist in clarifying the complex issues involved in its treatment and has led to the authors ' current method of approach. Originating from the deep posterior compartment of the leg, the tibialis posterior has extensive insertions in the foot, with the largest portion inserting into the navicular tuberosity and smaller insertions into each of the major tarsal bones and metatarsal bases two, three, and four. There are also numerous slips which blend into the ligamentous structures of the midtarsus as well as into the fibers of the peroneus longus tendon (1). From Wyckoff Heights Medical Center Residency Program, Brooklyn. NY. Address correspo ndence to: Alison D. Silhanek, DPM, 126 E. Main Street, Suite I, East Islip, NY 11730. Received for publication October 1998; accepted in revised form for publication December 1998. The Journal of Foot & Ankle Surgery 1067-25 16/99/3802-01 16$4.00/0 Copyright © 1999 by the American College of Foot and Ankle Surgeons

116

THE JOURNAL OF FOOT & ANKLE SURGERY

This extensive insertional network translates into complexity of function. Its insertion at the talonavicular jo int makes the posterior tibial tendon (PIT) an adductor of the midtarsal joint, directly opposing the peroneus brevis. In addition, as the surrounding ligaments act to prevent extremes of motion across the midtarsus, the PIT's insertional fibers to these ligaments reinforce their stabilizing power, effectively buttressing the medial arch (1). While a rupture of this tendon theoretically can be traumatic or degenerative in origin, many authors assert that injuries are not likely to cause rupture unless the tendon is already weakened by degenerativ e changes (2, 3). As this disorder often occurs in a foot which was already pronated, PIT dysfunction may begin as an overuse injury: in an attempt to stabilize an otherwise hypermobile structure, additional stress is placed on the tendon (1). Repetitive stress produces microtears and may elicit an inflammatory response, or tenosynovitis, in the tendon and its synovial sheath, eventually causing attenuation of the tendon fibers. If the stresses are more severe, the microtears may instead be followed by larger intrasubstance tears and ultimately by complete rupture (4). Weakening of the PIT then leads to a cascade of structural effects on the foot. These effects are initiated when ground reactive forces encourage forefoot abduction even as the midtarsal joint supinates in preparation for propulsion. In a fully functioning foot, these two opposing

forces are controlled as the PTT and talonavicular ligaments work in concert to prevent extremes of motion. However, if the PTT is ineffective, the stresses of body weight and gravity are carried solely by the ligamentous structures (1). The excess tension on the ligaments leads to their elongation allowing abnormal motion and, ultimately, instability and subluxation of the talonavicular joint. Without the buttressing effect of the PTT, the talus plantarflexes, adducts, and moves anteriorly, causing a loss of medial arch height. Meanwhile, the peroneus brevis contributes to the instability by promoting forefoot abduction at the midtarsal joint (5). These latter two effects provide the clinical hallmarks of PTTD: pes planovalgus and forefoot abduction. However, it is important to realize that this disorder comprises a continuum, with changes in the tendon ranging from tenosynovitis to full rupture. Similarly, associated changes in the foot may begin with mild loss of arch height, but eventually can result in irreversible subluxation of the talonavicular joint and subsequent arthritic changes. In 1989, Johnson and Strom proposed a three-stage system on which to follow the course of PTTD (Fig. 1). This classification makes it possible to devise treatment regimens based on the stage of dysfunction. For stage I patients, Johnson and Strom suggest conservative measures (6). Unfortunately, due to the insidious onset and dull, aching nature of their pain, many patients present to a physician only after significant structural deformities exist. However, as with any condition, conservative measures should initially be attempted and may consist

Stage I: • Pain is localized along course of PTT • Tendon length is normal • Alignment of hindfoot- forefoot complex is normal Stage II: • PTT is enlarged and elongated as well as functionally incompetent • Foot is in pes planovalugus • Deformity is mobile, with each component of deformity remaining flexible Stage III: • Foot is in pes planovalgus with forefoot abduction at the talonavicular joint • Deformity is fixed, such that laterally subluxed navicular cannot be reduced into proper position on the head of the talus • May have pain laterally FIGURE 1

Johnson and Strom staging of PTIO (6).

of immobilization, bracing, orthoses, and nonsteroidal anti-inflammatories (7). When conservative measures fail, the practitioner must begin to consider the various forms of surgical management. For late stage I-II dysfunction, Johnson and Strom advocate soft-tissue reconstruction procedures (6), ranging from debridement and decompression of the stenosed tendon sheath, to distal tendon advancement, augmentation, or transfer procedures. Previous studies have found that while these procedures provide initial symptomatic relief, the physical alignment and appearance of the foot does not change postoperatively, and the medial longitudinal arch continues to sag over time (5, 8, 9). These studies illustrate the inadequacy of soft-tissue procedures as a sole means of correction for PTTD, because they fail to address the structural deformity at the midtarsal joint. While a stage II deformity may still be flexible, any subluxation of the talonavicular joint indicates that a loss of ligamentous and joint integrity has already occurred (8). This being the case, soft-tissue procedures alone will not be able to recreate stability properly in all but the mildest cases of this disorder. Historically, the procedure of choice for late stage II-III PTTD has been the triple arthrodesis. Unlike softtissue procedures, the triple arthrodesis can reposition the malaligned joints and then create stability through fusion of the rearfoot complex (2). Its major drawback, however, is the loss of motion of the entire rearfoot. More recently, isolated arthrodeses have been found to impart stability successfully to the affected joint while still maintaining some motion at adjacent joints (10). The authors' choice of an isolated talonavicular arthrodesis is contingent upon the biomechanics of PTTD: a fusion of this joint addresses the deformity at its apex, recreates stability in a hypermobile foot, and prevents any further medial arch collapse. In addition, calcaneal osteotomies have been advocated to restore proper functional mechanics to the rearfoot while preserving mobility (11, 12). One of the most common calcaneal osteotomies, the Evans lateral column lengthening procedure, essentially adducts the forefoot and allows the navicular to be repositioned on the head of the talus. In addition, by lengthening the lateral column, this procedure increases the lever arm of the peroneus longus, thereby plantarflexing the first ray and helping to restore height to the medial longitudinal arch. The Evans procedure thereby allows a medial translocation of the forefoot that cannot be achieved as effectively with a softtissue release and arthrodesis alone. After completion of the Evans procedure, the talonavicular joint is fused in the appropriate position, providing a stability not furnished by the calcaneal osteotomy alone (Fig. 2). Therefore, this combination of procedures creates a more proper structural alignment while obviating the need for fusion of the entire rearfoot complex. The purpose of this retrospective VOLUME 38, NUMBER 2, MARCH/APRIL 1999

117

study is to present the authors' experien ce with the combination of the Evans calcaneal osteotomy and talonavicular arthrodesis for PTTD.

Materials and Methods

FIGURE 2 Case #1. A, Preoperative view, exhibiting severe co llaps e of med ial longitudinal arch. B, Postoperative view , approximately 30 months after talon avicular fusion and Evans calcaneal osteotomy, with a restoration of the medial longitudinal arch .

Twelve patients underwent an Evans lateral column lengthening procedure and talonavicular arthrodesis by the senior authors (C.M.L, L.N.D.) over a 6-year period (Table 1). There were 10 females and two males, and the mean patient age was 48.7 years (range 37-68 years). Patient #3 had a history of rheumatoid arthritis; all other past medical histories were noncontributory. None of the patients could relate a specific incident of trauma to the affected area. The mean duration of symptoms before surgery was 17.0 months (range 6-36 months). Conservative treatment consisted of rest, immobilization, nonsteroidal antiinftammatories, orthotics, and corticosteroid injec tions into the PTT sheath followed by cast immobilization. Patient #7 (Fig. 3) had initially been treated by another physician with debridement of the P1T sheath and isolated soft-tissue reconstruction with reattachment of the tendon

TABLE 1 Composite patient data

Age

Foot Affected

Sex

Length of Symptoms Before Surgery

Stage of Dysfunction (Johnson and Strom)

Procedure Performed

Case 1

68

left

Female

6 mont hs

III

TN fusion, Evans

Screw entered subtalar joint

Case 2

44

Right

Female

10 months

II

TN fusion , Evans, PIT sheath release

Screw irritation

Case 3

46

Left

Female

36 months

III

STJ fus ion, TN fusion , Evans, PTT sheath release

None

Case 4

51

Right

Male

6 months

II

TN fus ion, Evans , PTT sheath release

None

Case 5

39

Left

Female

36 month s

II

TN fusion, Evans

None

Case 6

54

Right

Female

10 months

II

TN fus ion , PTT sheath release

Screw irritation

Case 7

53

Right

Female

6 months

III

TN fus ion, Evans

Sup erficial wound dehiscence

Case 8

50

Left

Female

18 months

II

TN fusion, Evans

Non e

Case 9

37

Left

Mal e

34 months

III

TN fusion, Evans

Nonunion of TN fus ion

Case 10

45

Right

Female

8 mon ths

III

TN fusion, Evans, PTT sheath release

None

TN , talonavicular; PIT, posterior tibial tendon; STJ, subtalar joint.

118

THE JOURNAL OF FOOT & ANKLE SURGERY

Complicat ions

FIGURE 3 Case #7. A, Preoperative AP radiograph, demonstrating severe abduction of the forefoot on the rearfoot. B, Preoperative lateral radiograph. Note retained internal fixation from previous PTI soft-tissue reconstruction procedure. C, Postoperative AP radiograph, with restoration of proper forefoot to rearfoot transverse plane relationship. D, Postoperative lateral radiograph, with a decrease in the talar declination angle.

VOLUME 38, NUMBER 2, MARCH/APRIL 1999

119

TABLE 2

Pre- and postoperative radiograph ic measurements and scoring

Length of Follow up

Preop X-ray Findings

Postop X-ray Findings

Preop AHF" Total? Score/100

Postop AHF Score/100

Preop AHF Subjective? Score/60

Postop AHF Subjective Score/60

Case 1

36 mont hs

TNd-56 Tce-26 TD' -40

TC-14 TD-24

62

81

38

48

Case 2

30 months

TN-10 TC-2 TD-36

TC-12 TD-26

22

81

6

48

Case 3

60 months

TN-7 TC-6 TD-32

TC-8 TD-29

50

93

36

60

Case 4

24 months

TN-6 TC-12 TD-35

TC-16 TD-30

67

80

36

45

Case 5

24 months

TN-41 TC-12 TD-30

TC-4 TD-26

42

83

15

48

Case 6

36 months

TN-32 TC-14 TD-42

TC-3 TD-21

42

83

19

50

Case 7

72 months

TN-39 TC-26 TD-40

TC- 14 TD-30

48

90

35

50

Case 8

8 months

TN-29 TC-16 TC-35

TC-10 TD-29

31

65

9

37

Case 9

24 months

TN-25 TC-25 TD-24

TC-14 TD-20

23

83

9

48

Case 10

36 months

TN-26 TC- 14 TD-28

TC-4 TD-14

36

91

31

53

AOFAS score abbreviations: BAHF, ankle-hindfoot; btotal, total score (= subjective + objective findings); Csubject ive, subjective findings only. X-ray Abbreviations : dTN, talonavicular angle; eTC, talocalcaneal angle; ' TD, talar dec lination angle.

to the navicular with a screw and washer. She then presented to a senior author (C.M.L.) 6 months later with a continued complaint of pain and a progression of her medial arch collapse. The indications for surgery were continued pain despite 6 months of conservative treatment and a minimum classification of stage II PTTD (6). Any adjunctive procedures are listed. Patients in the earliest years of the study had a release of their PIT sheath; this procedure was later discontinued as its added effectiveness to a talonavicular fusion was found to be questionable. The mean duration of postoperative follow-up was 35 months (range 8-72 months). Ten of the 12 patients were available for a follow-up examination. These 10 patients completed a survey , were re-exami ned, and subjective and objective findings were recorded based on the guidelines of the American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Rating Scale (Table 2) (13). 120

THE JOURNALOF FOOT & ANKLE SURGERY

Analysis of the findings was then performed using the paired t -test. In addition, preoperative radiographs were evaluated for measurements of the talocalcaneal and talonavicular angles on the AP view and the talar declination angle on the lateral view. Radiographs taken at the most recent follow-up examination are designated as the postoperative radiog raphs. These views were evaluated for changes in talocalcaneal and talar declination angles as well as for any evidence of postoperative degenerative changes in surrounding joints. Operative Procedure

A curvilinear incision is made extending from the distal tip of the medial malleolus to the medial margin of the first naviculocuneiform jo int, and is deepened to the deep fascia. The capsul ar and periosteal structures are freed

from the underlying talus and navicular to create a subperiosteal plane across the dorsal surface of the midtarsus. The opposing surfaces of the talonavicular joint are then cleared of all cartilage using a roto-osteotome or curette. Attention may then be directed to the lateral aspect of the ankle where a second incision is made in an oblique fashion just inferior to the sinus tarsi. Dissection is carried to the level of the calcaneus, where the periosteal and capsular structures are freed from the dorsal and lateral surfaces of the calcaneus and cuboid, taking care to preserve the dorsal calcaneocuboid ligament. Using a power oscillating saw, a through-and-through osteotomy of the calcaneus is performed from lateral to medial 1.5 em proximal to the calcaneocuboid joint, and a bicortical allograft is inserted into the osteotomy site. The size of the graft is chosen such that it causes relocation of the navicular onto the head of the talus (lateral graft width ranged between 0.5 and 1.0 em). The authors prefer either no fixation or one Kirschner wire at the site of the graft. The talonavicular joint may then be fused with a variety of fixation methods. Most commonly, crossed 4.0-mm cancellous screws were placed, after which the incisions were closed in layers. Patients are placed in below-knee casts and made nonweightbearing for 8 weeks, with serial radiographs taken to gauge osseous union and integration of the allograft.

There were no intraoperative complications. Postoperatively, patient #7 experienced superficial dehiscence of the medial incision, which healed after 2 weeks of local wound care. Patient #9 bore weight on the affected foot throughout the recovery period and the talonavicular fusion site was noted to lack signs of osseous union at 8 months postoperatively. The Evans osteotomy did demonstrate integration of the allograft. The patient returned to the operating room for removal of hardware and refusion of the talonavicular joint using crossed 4.0-mm cancellous screws. The patient was followed postoperatively with external bone stimulation, casting, and immobilization and went on to uneventful fusion at 6 months. Patient #6 dropped a bottle on the medial operative site at 8 weeks postoperatively. Initial radiographs at that time showed mild «3 mm) displacement of the fusion site. The patient was recasted, immobilized, and made nonweightbearing with crutches and went on to uneventful fusion at 16 weeks. Two patients experienced irritation at the site of the screw placement. Both patients found relief of discomfort after screw removal. The talonavicular fusion screw in patient #1 was found on immediate postoperative radiographs to enter the subtalar joint. The patient was advised on the possible need for screw removal if discomfort occurred, but to date has not desired screw removal.

Results Discussion

The mean preoperative ankle-hindfoot total score was calculated to be 42.31100 (range, 22-67). Postoperatively, the mean score increased to 831100 (range 65-93). The difference in these scores was found to be statistically significant for p < .001. Subjectively, patients had a mean preoperative score of 23.6/60 (Range, 6-38), which demonstrated a significant improvement (p < .001) postoperatively to a mean of 48.7/60 (range, 37 -60). Patients demonstrated a large range of preoperative talonavicular and talocalcaneal angles. The mean preoperative talonavicular angle was 27°. The mean preoperative talocalcaneal angle was 15.3°. The latter angle changed postoperatively to a mean of 9.9°. It should be noted that in three patients whose preoperative talocalcaneal angle was well within normal limits, the postoperative talocalcaneal angle actually increased. The mean preoperative talar declination angle was 34.4°. Postoperatively, the mean talar declination angle was 24.9°. An evaluation of postoperative radiographs demonstrates mild osteophytic lipping at the dorsal naviculocuneiform joint in two patients. Neither patient had any associated complaints of pain or stiffness at the most recent follow-up examination. No changes were seen at the subtalar, calcaneocuboid, or ankle joints on postoperative radiographs in any patients.

In this study, radiographic findings were of little help in either diagnosing PTTD or in gauging its severity. The AP talocalcaneal angle was the least consistent angle, with many patients demonstrating normal preoperative values and the postoperative change was found to be insignificant at p < .058. Other authors have noted that the only consistent radiographic indicator of the condition is an increase in the talonavicular angle (12, 14). Many of our patients did demonstrate a dramatically abducted forefoot with an increased talonavicular angle. However, three patients had normal preoperative talonavicular angles but significantly high talar declination angles, suggesting that, for some patients, the sagittal plane component of the deformity can dominate. This seems to be dependent on the patient's foot type; patients whose subtalar joint axis is fairly vertical will exhibit a larger amount of transverse plane deformity and forefoot abduction, while patients with a more horizontal subtalar joint axis will exhibit eversion and more pronounced medial arch collapse. For all of our patients, the talar declination angle was abnormally increased and there was a significant postoperative change (p < .001). The Ankle-Hindfoot Rating Scale was used for standardization purposes. However, the use of this particular VOLUME 38, NUMBER 2, MARCH/APRIL 1999

121

rating system presented one difficulty with respect to this study. As the authors' choice of procedures included a rearfoot fusion, rearfoot motion invariably decreased postoperatively and was a goal, not a complication of the procedure. While patient scores still include the "hindfoot motion" criterion, it should be noted that when scores including and excluding this criterion were compared, those scores without the criterion were significantly higher (p < .05). Some authors argue against the use of isolated arthrodeses because of the possibility of postoperative arthrosis in adjacent joints. Astion and associates demonstrated that the talonavicular joint has the greatest amount of preoperative motion as compared to the subtalar and calcaneocuboid joints. Therefore, a fusion of the talonavicular joint causes the greatest loss of motion at the other rearfoot joints (15). However, it has also been shown that, while simulated fusion of the talonavicular joint significantly reduces talar mobility, it produces little effect on ankle joint motion and calcaneal eversion (16), suggesting that patients with adequate preoperative motion at the ankle and subtalar joints can compensate at these joints for a loss of talonavicular motion. With an average follow-up of 35 months, no patient in our study has had complaints of pain in adjacent joints, and only two patients demonstrated radiographic changes at the naviculocuneiform joint. Our patients showed significant improvement both in their subjective discomfort and in the structural alignment and function of their feet postoperatively. All of the patients demonstrated a decrease in pain and in their need for supportive measures, such as a cane or walker, and an improvement in the distance they could walk. They also exhibited a stable, plantigrade foot and improved gait. This study was limited by its small size and its relatively brief follow-up period. In addition, the most significant complication among our patients was one nonunion in a patient who was noncompliant throughout the recovery period despite judicious preoperative education. This case illustrates the importance of careful patient selection for these procedures. Other than this refusion, no patient in this study required subsequent additional fusions. Conclusion

The authors have found that the Evans lateral column lengthening procedure and talonavicular fusion provide

122

THE JOURNAL OF FOOT & ANKLE SURGERY

consistent results for the treatment of PTTD. By addressing the structural deformity at its apex, this combination of procedures reduces the deformity and recreates stability in the medial longitudinal arch, precluding the need for a triple arthrodesis. References I. Mueller, T J. Acquired flatfoot secondary to tibialis posterior dysfunction: Biomechanical aspects. J. Foot Surg. 30:3-II, 1991. 2. Banks, A. S.. McGlamry, E. D. Tibialis posterior tendon rupture. J. Am. Podiatr. Med. Assoc. 77:170-176, 1987. 3. McMaster, P. Tendon and muscle ruptures. J. Bone Joint Surg. 15:705-722, 1933. 4. Fredenburg, M., Tilley, G., Yagoobian, E. M. Spontaneous rupture of the posterior tibial tendon secondary to chronic nonspecific tenosynovitis. J. Foot Surg. 22:198-202, 1983. 5. Mann, R. A., Thompson, F. M. Rupture of the posterior tibial tendon causing flat foot: Surgical treatment. 1. Bone Joint Surg. 67-A: 556-561, 1985. 6. Johnson, K. A., Strom, D. E. Tibialis posterior tendon dysfunction. Clin. Orthop. 239:197-206, 1989. 7. Johnson, K. A. Tibialis posterior tendon rupture. Clin. Orthop. 177:140-147, 1983. 8. Funk, D. A., Cass, J. R., Johnson, K. A. Acquired adult flat foot secondary to posterior tibial-tendon pathology. 1. Bone Joint Surg. 68-A:95-102, 1986. 9. Kitaoka, H. B., Luo, Z., An, K. Reconstruction operations for acquired flatfoot: Biomechanical evaluation. Foot Ankle 19:203- 207, 1998. 10. O'Malley, M. J., Deland, 1. T, Lee, K. Selective hindfoot arthrodesis for the treatment of adult acquired flatfoot deformity: an in vitro study. Foot Ankle. 16:411-417, 1995. II. Pomeroy, G. C; Manoli, A. A new operative approach for flatfoot secondary to posterior tibial tendon insufficiency: a preliminary report. Foot Ankle 18:206-212, 1997. 12. Myerson, M. S., Corrigan, J., Thompson, F., Shon, L. C. Tendon transfer combined with calcaneal osteotomy for treatment of posterior tibial tendon insufficiency: a radiological investigation. Foot Ankle 16:712-718, 1995. 13. Kitaoka, H. B., Alexander, I. J., Adelaar, R. S., Nunley, J. A., Myerson, M. S., Sanders, M. Clinical rating systems for the anklehindfoot, midfoot, hallux, and lesser toes. Foot Ankle 15:349-353, 1994. 14. Dyal, C. M., Feder, J., Deland, J. T, Thompson, F. M. Pes planus in patients with posterior tibial tendon insufficiency: asymptomatic versus symptomatic foot. Foot Ankle 18:85-88, 1997. 15. Astion, D. J., Deland, J. T, Otis, 1. C., Kenneally, S. Motion of the hindfoot after simulated arthrodesis. J. Bone Joint Surg. 79A:241-245,1997. 16. Hintcrmann, B., Nigg, B. M. Influence of arthrodeses on kinematics of the axially loaded ankle complex during dorsiflexionJplantarflexion. Foot Ankle 16:633-636, 1995.