Effect of the additional first ray osteotomy on hindfoot alignment after calcaneal osteotomy for the correction of mild-to-moderate adult type pes plano-valgus

Abstract

Purpose:

To determine the effect of the additional first ray osteotomy on hindfoot alignment for the correction of pes plano-valgus.

Methods:

Data obtained from 37 consecutive patients recruited from 2006 to 2014 who underwent medial displacement calcaneal osteotomy (MDCO) alone (group H) or MDCO followed by medial cuneiform opening wedge osteotomy (MCOWO) (group HF) with a minimum 1-year follow-up were reviewed retrospectively. The mean follow-up periods were 34 and 32 months.

Results:

Degree of decrease of Talonavicular coverage angle (TNCA) via surgery or postoperative TNCA on standing foot AP radiographs were not significantly different between group H and HF (p = 0.287). The calcaneal pitch angle and medial cuneiform height on the standing foot lateral radiographs was significantly increased after operation in group HF (p = 0.01), there was a significant difference with group H as well (p = 0.033). In group HF, the Meary’s angle was significantly decreased after operation, a significant difference compared to group H (p = 0.009). Hindfoot alignment angle on the hindfoot alignment view was decreased after operation in both groups but was not significantly different between both groups (p = 0.410). Hindfoot alignment ratio was also increased after the operation in both groups, but was not different between two groups (p = 0.783).

Conclusion:

The additional first ray osteotomy using MCOWO had no correctional power for hindfoot correction, although it caused improvement in some radiographic parameters.

Keywords

outcome studies pes planus statistical analysis

Introduction

Pes plano-valgus in adults, which is caused by posterior tibial tendon (PTT) dysfunction, is a deformity characterized by loss of the medial longitudinal arch, forefoot abduction and supination, and hindfoot valgus. The PTT drives inversion of the hindfoot during the stance phase of gait; therefore, PTT dysfunction causes a hindfoot valgus deformity, resulting in tearing of the stretched PTT and tightening of the Achilles tendon. Lateral impingement between the calcaneus and lateral malleolus might occur, due to which symptoms can move to the lateral side with the progression of the deformity. Surgical treatment options vary, from soft tissue realignment such as flexor digitorum longus (FDL) transfer, to bone procedures such as medial displacement calcaneal osteotomy (MDCO) for hindfoot valgus correction and medial cuneiform opening wedge osteotomy (MCOWO) handling the first ray for forefoot supination correction. However, MDCO is the cornerstone reconstruction procedure for pes plano-valgus deformity.¹

The authors retrospectively reviewed and compared the data obtained from patients who underwent MDCO alone and calcaneal medial sliding osteotomy combined with MCOWO to determine the effect of the additional first ray osteotomy on the hindfoot alignment for the correction of pes plano-valgus. We hypothesized that the additional first ray osteotomy would not have a significant effect on hindfoot alignment.

Materials and methods

Patient selection

The study included 37 consecutive patients (37 cases) who underwent only MDCO or MDCO followed by MCOWO from April 2006 to June 2014. The duration of postoperative follow-up was at least 1 year. In all cases, surgery was performed when >6 months of conservative treatment had failed. The exclusion criteria were (1) age < 18 years; (2) congenital type pes planus deformity accompanied by talocalcaneal, calcaneonavicular, or naviculocuneiform coalition; (3) systemic inflammatory conditions such as rheumatoid arthritis; (4) history of trauma that could have caused foot deformity; and (5) paraplegia.

The number of isolated hindfoot correction procedures using MDCO (group H) and simultaneous hindfoot and forefoot correction using MDCO followed by MCOWO (group HF) were 17 and 20, respectively.

Operative technique

Among 37 cases, the procedure was performed with the patient under general anesthesia in 21 cases (57%) and spinal anesthesia in 16 (43%). The mean operative time was 33 (range, 21–44) minutes for group H and 48 (range, 34–52) minutes for group HF. The procedure was performed with the patient in the semi-lateral position with support under the patients’ hip on the affected side. A pneumatic tourniquet was applied to prevent bleeding.

An oblique incision was made on the lateral side of the hindfoot, making a 45° angle with the calcaneal inferior side. The periosteum was dissected and calcaneal osteotomy was performed perpendicular to the lateral aspect of the calcaneus 1 cm posteriorly from the subtalar joint. The calcaneus was shifted 10 mm medially. Two 5.0 cannulated screws were fixed firmly from the calcaneal tuberosity crossing the osteotomy site. The operation was complete at this point in group H, while a further procedure was performed on the forefoot in group HF.

In group HF, the patient was placed supine and the support under the affected hip was removed. A 3-cm incision was made along the medial side of the FHL tendon. On confirming the medial cuneiform bone, vertical osteotomy was performed leaving the plantar side intact. A small and narrow 10-mm osteotome was inserted to open the osteotomy site, after which a lamina spreader was inserted for further opening and maintenance. Either a low profile opening wedge osteotomy plate with a 6-mm wedge (Arthrex, Naples, Florida, USA) into the opening gap or a low profile plate with bone graft was fixed or screws were fixed to secure the osteotomy site.

Below-knee cast immobilization was maintained for 6 weeks after the operation, and weight bearing was excluded during this time. The cast was removed after 6 weeks, radiographs were taken to determine the status of the union, and the patient was encouraged to slowly start walking.

Assessment

In order to determine the extent of pes forefoot abduction correction, the talonavicular coverage angle (TNCA) was measured preoperatively and during the final follow-up by using standing foot AP radiographs. Calcaneal pitch angle (CPA), talo-first metatarsal angle (Meary’s angle) and the distance from the floor to the plantar side of the medial cuneiform bone (medial cuneiform height) were measured to determine the extent of medial arch by using lateral radiographs. In order to examine the extent of correction of hindfoot valgus, hindfoot alignment angle (HAA), which is formed by the axis of the tibia and the calcaneus as well as the hindfoot alignment ratio (HAR),² which is defined as the ratio of the medial calcaneal width to total hindfoot width were measured in the hindfoot alignment view.³ Clinical results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score,⁴ which included 40 points for pain, 45 for function, and 15 for alignment, with a total of 100. Furthermore, cases with complications were followed and analyzed to determine how the complications affected the clinical results.

All operations and a follow-up examination were performed by a single surgeon in the same manner. This retrospective study was approved by our institution’s ethical review committee. The Wilcoxon rank sum test as implemented in SPSS 18 was used for the statistical analysis of all variables, and a p value < 0.05 was considered to represent statistical significance.

Results

The mean age and follow-up duration were not significantly different between two groups. The demographic parameters of each group are summarized in Table 1.

Table 1.

Patient demographics in both groups.

	Group H (n = 17)	Group HF (n = 20)	p Value
Sex (M:F)	11:6	5:15
Age (years)	46.06 ± 11.20	46.25 ± 17.83	0.847
Affected side (L:R)	11:6	15:6
Follow-up duration (months)	34.24 ± 15.23	32.62 ± 14.34	0.411
Anesthesia	General 10, spinal 6	General 11, spinal 10

Degree of decrease in TNCA via surgery or postoperative TNCA on standing foot AP radiographs were not significantly different between both groups (p = 0.287).

The CPA on the standing foot lateral radiographs was significantly increased after operation in group HF (p = 0.01), but there was a significant difference with group H as well (p = 0.033). Preoperative Meary’s angle was 10.99 ± 6.17 (ranged from −7.1° to −13.5°) and −10.20 ± 6.55 17 (ranged from −6.8° to −22.9°) in group H and HF respectively. In group HF, the Meary’s angle was significantly increased after operation (p = 0.005), which showed a significant difference compared to group H (p = 0.009). The medial cuneiform height was significantly increased in group HF (p = 0.001), showing a significant difference compared to group H (p = 0.01).

The HAA on the hindfoot alignment view was decreased after operation in both groups but there was no significant difference between both groups (p = 0.410). The HAR was also increased after the operation in both groups, but was not different between both groups (p = 0.783) (Figures 1 and 2).

Figure 1.

Pre-(a, b, c) and postoperative 1-year follow-up (d, e, f) radiographs of 28-year-old female patient in group H showed a significant improvement of hindfoot alignment angle and ratio.

Figure 2.

Pre-(a, b, c) and postoperative 1-year follow-up (d, e, f) radiographs of 37-year-old male patient in group HF showed a significant improvement of Meary’s angle, calcaneal pitch angle, medial cuneiform height as well as hindfoot alignment angle and ratio.

The AOFAS hindfoot score improved postoperatively, but without significant differences between both groups (p = 0.697). Postoperative infection, nonunion, malunion, or delayed union was not seen in either group. The mean and SDs of each radiographic parameter in group H and HF are listed in Table 2.

Table 2.

Pre and postoperative radiographic parameters of each group.

		Group H (n = 17)	Group HF (n = 20)	p Value
TNCA	Pre-op	22.59 ± 10.47	23.19 ± 9.79	0.795
	Post-op	20.91 ± 8.74	21.02 ± 8.87	0.287
	p Value	0.32	0.35
CPA	Pre-op	11.48 ± 3.27	12.44 ± 4.12	0.569
	Post-op	12.11 ± 5.40	16.30 ± 4.71	0.033
	p Value	0.033	0.01
Meary’s angle	Pre-op	−10.99 ± 6.17	−10.20 ± 6.55	0.723
	Post-op	−9.71 ± 3.88	−6.46 ± 7.12	0.009
	p Value	0.521	0.005
Medial cuneiform height (mm)	Pre-op	15.83 ± 5.85	15.80 ± 3.12	0.906
	Post-op	16.08 ± 4.85	23.01 ± 2.78	0.01
	p Value	0.12	0.001
HAA	Pre-op	13.02 ± 10.66	12.29 ± 7.51	0.868
	Post-op	5.19 ± 6.88	3.29 ± 8.33	0.410
	p Value	0.015	0.01
HAR	Pre-op	0.16 ± 0.02	0.19 ± 0.01	0.794
	Post-op	0.36 ± 0.07	0.33 ± 0.08	0.783
	p Value	0.0005	0.0005
AOFAS	Pre-op	56.91 ± 10.42	53.49 ± 9.79	0.785
	Post-op	86.32 ± 12.43	83.39 ± 10.59	0.697
	p Value	0.01	0.01

AOFAS: American Orthopaedic Foot and Ankle Society; HAR: hindfoot alignment ratio; HAA: hindfoot alignment angle; CPA: calcaneal pitch angle; TNCA: talonavicular coverage angle; Post-op: postoperative; Pre-op: preoperative.

Discussion

In adult-type pes plano-valgus, the peroneal tendon, which abducts and everts the foot has a normal function, while the PTT is dysfunctional. This results in forefoot abduction and hindfoot valgus. Furthermore, the Achilles tendon everts the foot in case of hindfoot valgus, which aggravates the deformity caused by PTT dysfunction.

Generally, operative treatment is considered when conservative treatment shows no effect in adult-type pes plano-valgus. Operative goals include pain relief, prevention of deformity aggravation, improvement of muscle power and accommodation,^5,6 and maintenance of foot flexibility. The soft tissue procedure includes repair of the spring ligament, imbrication of the talonavicular joint capsule, and reinforcement of the PTT using the FDL, FHL, or peroneus brevis. These are rarely performed as isolated procedures and are usually accompanied by an MDCO as well as additional corrective osteotomies.¹ The ideal bony procedure to treat pes plano-valgus realigns the hindfoot and corrects the deformity.⁷ MDCO, which is the cornerstone reconstruction procedure, can be performed to correct the hindfoot valgus deformity.¹ MCOWO is usually performed when the forefoot supination deformity coexists. Subtalar, double, or triple arthrodesis can be considered in case of a severe deformity that is not corrected with soft tissue reconstruction or one of the osteotomies mentioned above.

Through this study, we found that MCOWO after MDCO did not have a significant effect on hindfoot alignment but did affect sagittal alignment.

MDCO, which reduces the antagonistic effect of the Achilles tendon by moving the laterally attached Achilles tendon insertion site medially, was first described by Gleich.⁸ It restores the tension of the medial tendons and ligament of the hindfoot and reduces the torque to the subtalar joint by reducing the distance between the point of heel and the floor and the longitudinal axis of lower extremity.⁹

Myerson et al.¹⁰ reported the significant improvement in the Meary’s angle from −27° to −12° and medial cuneiform height from 7 to 19 mm after combined FDL tendon transfer and MDCO in 129 patients. Marks et al.¹¹ reported that there was no significant change in the Meary’s angle while the CPA and medial cuneiform height showed significant increases after the same procedure as Myerson et al.¹⁰ described for 14 patients. Sammarco and Hockenbury¹² mentioned no significant radiologic differences after the same procedure and Park et al.¹³ reported that MDCO without FDL tendon transfer for flexible flatfoot could lead to improved clinical outcomes, although the restoration of the medial longitudinal arch was not clinically significant.

In our study, MDCO was performed when either the HAA was more than 10° or the HAR was less than 0.2. The Meary’s angle, CPA, and medial cuneiform height were not significantly changed after surgery in group H, while HAA and HAR were significantly improved on the hindfoot alignment view. We believe that the reason for symptom improvement in group H resulted from hindfoot valgus correction and reinforcement of ankle inversion power.

MCOWO is generally chosen in case of remnant forefoot supination after hindfoot correction because MDCO cannot correct the fixed forefoot supination deformity.¹⁴ MCOWO has the advantage of correcting the forefoot supination deformity, therefore avoiding arthrodesis.^15
–17 It is generally believed that the two biggest advantages of MCOWO were a higher union rate than that of midfoot or ankle joint arthrodesis and a varied degree of correction with a preservation of first ray motion. However, to the best of our knowledge, no study has been performed to reveal the effects of forefoot corrective surgery on hindfoot alignment. Hirose and Johnson ¹⁴ reported a good result after MCOWO for 16 cases of pes plano-valgus combined with fixed forefoot supination deformity. In their study, the Meary’s angle, CPA, and medial cuneiform height were significantly changed, but they did not mention any change in hindfoot alignment.

Lateral column lengthening, another surgical option, can correct forefoot abduction and hindfoot valgus and improve postoperative TNCA, preserving hindfoot motion.^18,19 Kadaika²⁰ presented that the root cause of a flexible flatfoot deformity was failure of the medial column stabilizers, rather than a shortened lateral column for adult-acquired flatfoot. He also insisted that lateral column lengthening was best utilized for pediatric/adolescent patients or for those who had flatfoot for their entire life, as they had a developmentally shortened lateral column and thus isolated medial column stabilization was not suitable. In our study, TNCA did not change in either group, meaning that the procedure did not have the ability to correct forefoot abduction.

The main limitation of this study is the lack of comparison with result of first ray forefoot corrective osteotomy without correcting hindfoot alignment. We did not compare this group to others because forefoot correction was generally performed in case of remnant fixed forefoot supination after hindfoot correction operation. If this comparison had been performed, our hypothesis would have been better supported. The small number of patients and the retrospective design of the study are the other limitations.

In conclusion, when correcting the hindfoot valgus deformity, which is the main cause of lateral impingement syndrome in the progressed adult-type pes plano-valgus, hindfoot correction using MDCO is inevitable. The additional first ray osteotomy using MCOWO could not correct hindfoot alignment, although it caused improvement in sagittal alignment in some radiographic parameters.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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