Functional and patient reported outcomes following lateral hallucal sesamoidectomy

Background
Lateral hallucal sesamoidectomy is an infrequently performed procedure indicated for patients with sesamoid pathology failing conservative treatment. Concerns exists regarding patient satisfaction, plantar scar pain, hallux malalignment and metatarsophalangeal joint (MTPJ) movement restriction following sesamoidectomy.

This study aims to assess patient satisfaction after lateral hallucal sesamoidectomy via the plantar approach.

Methods
In this retropective study with prospective follow-up, all patients who underwent lateral hallucal sesamoidectomy between January 2004 and December 2017 were reviewed. Twelve patients (14 ft.) were available for final assessment. Outcome measures were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) clinical rating scale and the Self-Reported Foot and Ankle questionnaire (SEFAS). Patients were assessed clinically and radiologically. The average postoperative follow-up was 111.5 months (range 28–177 months).

Results
All patients reported excellent outcome scores with a mean SEFAS score of 46.08 (range 43–48) and a mean AOFAS score of 92.33 (range 78–100) at final follow-up. All twelve patients reported their outcome as being excellent. No malalignment was noted clinically, however, three patients had a noticeable increase in the gap between the hallux and second toe when compared to the contralateral side. Range of motion at the MTPJ was preserved with a mean dorsiflexion of 80.83° (range 70–90°) and a mean plantarflexion was 25.83° (range 0–30°). None of the patients experienced any pain, discomfort or irritation related to the plantar scar. One patient developed neuroma like symptoms in the first web space.

Conclusion
Lateral hallucal sesamoidectomy via a plantar approach is an effective and reliable treatment option as demonstrated by the high levels of patient satisfaction, preservation of function, excellent PROM scores and limited complications in this study.

Level of evidence
Level 4.

Introduction
The hallucal sesamoids are a pair of seed shaped bones with the medial (tibial) sesamoid being longer and slightly more distal than the lateral (fibula) sesamoid [1]. They are enveloped within the respective medial and lateral flexor hallucis brevis (FHB) tendons and articulate with the plantar surface of the first metatarsal head [2]. The capsular-ligamentous-sesamoid complex comprising the FHB, adductor hallucis, abductor hallucis, plantar plate and collateral ligaments provides most of the stability to the metatarsophalangeal joint (MTPJ) [3]. Anatomical factors influencing mechanical load on the sesamoids include the size of the sesamoids, absence of the crista, rotation of the metatarsals, ankle equinus deformity, pes cavus and a plantar flexed first metatarsal [2,4].

The sesamoids act as shock absorbers, dissipating forces during weight bearing. The lateral sesamoid being smaller absorbs less of the weight and is subjected to less loading and shearing forces rendering it less prone to injury compared to the medial sesamoid [[5], [6], [7]].

Sesamoid pain can result from a wide range of causes including acute fractures, stress fractures, acute bipartite diastasis, osteoarthritis, chondromalacia, AVN, infection, sesamoiditis and as part of inflammatory disorders. Sesamoiditis is usually seen with overuse and repetitive activity (Fig. 1, Fig. 2 ).

Lateral sesamoidectomy can be performed via a dorsal or plantar approach. The dorsal approach used to be the preferred approach because it avoided the possibility of causing wound problems or the formation of a painful scar that was thought to result from a plantar approach [[7], [8], [9]]. However, studies have shown good results with a plantar approach [[9], [10], [11]]. Furthermore, excision of the lateral sesamoid via a dorsal approach can be difficult with suboptimal exposure. One study noted that two of their seven patients who had a dorsal approach developed nerve entrapment and one patient developed hallux varus [11]. The adductor mechanism is also at greater risk of being damaged with a dorsal approach [1].

With regards to the general outcome following sesamoidectomy, earlier studies demonstrated unsatisfactory results in terms of persistence of pain and functional deficits, however, more promising results have been reported in the more recent literature [5,[11], [12], [13]].

A systematic review by Robertson et al. on the return to sport following sesamoid stress fractures (medial or lateral) found that sesamoidectomy offered quicker return to sport compared to ORIF (10,5 vs 11,8 weeks), but only 88% returned to baseline level of sporting activity after sesamoidectomy compared to 100% after ORIF [14].

Possible complications of lateral sesamoidectomy include development of a hallux varus deformity, clawing if the FHB is weakened or the plantar plate damaged, wound complications, painful scar formation, stiffness, development of neuromas or neuritis and metatarsalgia [7,11,13,15,16].

Reduction in push-off strength with sesamoidectomy has been reported by measuring the effective tendon moment arm with a supplied input force in cadaveric studies. Aper et al. showed a 10% and 16% reduction in push-off strength with medial and lateral sesamoidectomy respectively and a 30% reduction with total sesamoidectomies [17,18]. They also showed a significant reduction in the flexor hallucis longus (FHL) moment arm with lateral, medial and total sesamoidectomy [17]. Mann et al. reported that 12 out of 21 patients experienced push-off or flexion weakness after sesamoidectomy [12].

The aim of this study was to evaluate patient outcomes following lateral sesamoidectomy of the great toe with regards to alignment, painful scar formation, patient functioning and satisfaction.

Section snippets
Materials and methods
In this retrospective study with prospective follow-up, all patients who underwent lateral hallucal sesamoidectomy between January 2004 and December 2017 were reviewed. Seventeen patients were identified, 16 females and 1 male. Twelve of the 17 patients (14 ft.) were available for final clinical assessment. The mean age was 38.4 years (range 20–52 years) at the time of surgery. Indications for surgery are shown in Table 1 with the most common indication being sesamoiditis. All excisions were

Results
All patients reported excellent outcome scores with a mean of 46.08 (range 43–48) according to the SEFAS grading while the mean AOFAS score was 92.33 (range 78–100) at final follow-up (Table 2, Table 3). When asked if they considered the result of their procedures to be either excellent, good, fair or poor, all 12 patients reported their outcome as being excellent (Table 4).

Clinically, the MTPJ had a mean dorsiflexion of 80.83° (range 70–90°) while the mean plantarflexion was 25.83° (range

Discussion
Lateral hallucal sesamoidectomy is an infrequently performed procedure indicated for patients with sesamoid pathology failing conservative treatment. Unsatisfactory results were observed from earlier studies with Inge and Ferguson (41 cases – medial or lateral sesamoidectomies) noting a persistence of pain in 41% of patients while Mann et al. also reported poor results in their series of 21 sesamoidectomies with only 50% obtaining complete pain relief [5,12]. Leventen reported satisfactory

Conclusion
Lateral hallucal sesamoidectomy via a plantar approach is an effective and reliable treatment option as demonstrated by the high levels of patient satisfaction, preservation of function, excellent PROM scores and limited complications in this study.

Ethics statement
This study was approved by the university’s Human Research Ethics Committee (M180903).

Declarations of interest
None.

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