Sesamoiditis is a generic term that refers to a variety of painful conditions affecting the sesamoids under the head of first metatarsal. These conditions include fracture, chondromalacia, avascular necrosis (AVN) and mechanical overload.
The tibial (medial) and fibular (lateral) sesamoids bear 50% of the body weight, which increases to 300% during the push-off phase, which predisposes the sesamoids to various injuries. Certain activities render even higher risk of injuries to the sesamoids (wearing high-heeled shoes, dancing, sporting activities, a cavovarus foot and a rigidly plantarflexed first ray).
The sesamoids play an integral role in the dynamic function of the first MTP joint. Deterioration of function resulting from trauma, inflammation, fracture, or surgery can lead to significant disability. Although surgical intervention may become necessary in the treatment of a chronically painful conditions, the sesamoid complex should be preserved whenever possible.
If sesamoidectomy becomes essential, care should be taken to maintain the integrity of the remaining intrinsic muscles and capsule to maintain stability and function of the first MTP joint. A single diseased sesamoid can be removed with acceptable postoperative results if patients accept the potential risks; however, the resection of both sesamoids should be avoided unless absolutely necessary.
Imaging includes plain AP, lateral, oblique and dedicated sesamoid radiographs, which permit the evaluation of articular contours, joint space and bony alignment. If sesamoid fractures are missed, these may be complicated by delayed or non-union.
If suspected clinically with normal radiographs, CT or MRI is recommended. CT scans are considered more sensitive and specific for detection of acute fractures and also detect other conditions including periostitis, callus formation, articular irregularity, or pseudocyst formation.
MRI is useful in cases of suspected fractures as well as identifying stress reaction (marrow oedema in the absence of a visible fracture).
Sesamoid fracture can result from acute trauma or chronic repetitive injuries. The fracture of the tibial sesamoid is more common because it is the larger of the two and bears a greater mechanical stress.
Sesamoid fractures are often radiographically occult and may be confused with bipartite sesamoid. Fractures are characterised by sharp margins, whereas bipartite sesamoids have smoothly rounded and corticated margins.
Sesamoid problems can often be treated effectively with conservative management. Initial treatment includes a combination of NSAIDs and physical therapy. The local application of heat and cold may also be beneficial. Avoidance of repetitive activities that aggravate the symptoms, avoidance of walking barefoot or with shoes that do not provide good support, and short-term immobilisation of the affected foot may provide pain relief.
Metatarsal pads or moulded orthotic devices may also be of value. A stiff-soled shoe or a graphite insole can diminish MTP joint motion and relieve pain.
Taping of the great toe in some degree of plantar flexion also helps to relieve pressure on the sesamoids. Decreasing shoe heel height can reduce pressure on the involved sesamoid and relieve symptoms. Low energy extracorporeal shockwave therapy may also provide symptomatic relief in resistant cases. For patients who do not respond to these treatment modalities, injection with local anaesthetic and steroid is a reasonable next step.
Surgical excision may be considered when conservative treatment has proved unsuccessful; however, it is fraught with its own potential complications. The literature lacks sufficient information regarding postoperative results. Small series available in the literature have reported 41% to 50% relief of pain and resumption of normal activities.
Giurini et al. in reporting on sesamoidectomy for the treatment of chronic neuropathic ulceration beneath the first metatarsal head in diabetic patients, noted 2 of 13 patients developed clawing, although there only a short follow-up on these patients.
Dual sesamoid excision should in general be avoided, although sometimes it is uavoidable in rare cases. Abraham et al. reported one case of dual sesamoid excision after trauma, and Julsrud reported simultaneous osteonecrosis in a 22-year-old woman. In both these reports, an interphalangeal joint fusion was combined with a dual sesamoid excision.
Scranton and Rutkowski recommended a re-approximation of the defect created by surgery to minimise postoperative disability. Jahss recommended the repair of the defect in the flexor hallucis brevis similar to a repair of the quadriceps mechanism that is after a patellectomy.
The surgical approach used for sesamoid excision depends on which sesamoid is to be removed. The medial sesamoid can be approached through either a plantar-medial incision or a medial approach. Kliman et al. cautioned against using a plantar approach because of the proximity of the plantar digital nerves, and Mann et al. noted the possibility of the development of a painful plantar scar.
Mann and Coughlin have advocated a dorsolateral approach to resect the fibular sesamoid in cases of hallux valgus; and some other authors have advocated this approach for isolated fibular sesamoidectomy as well. Pinto et al. described a surgical excision of the lateral sesamoid through an extensive medial approach. Van Hal, Helal and Jahss recommended a longitudinal plantar incision adjacent to the fibular sesamoid for resection of a fibular sesamoid.
Aquino et al. reported their results in 26 feet that had undergone tibial sesamoid shaving for intractable plantar keratoses. An 89% subjective success rate was reported with this procedure. Because the intrinsic musculature was not disrupted, there was a negligible increase in the hallux valgus angle at final follow-up. The authors found minimal weakness at the first MTP joint. This procedure, however, is contraindicated in the presence of a plantar-flexed first metatarsal. In this situation, a dorsiflexion osteotomy is the treatment of choice for an intractable plantar keratotic lesion. If the first metatarsal is plantar flexed more than 8 degrees in relation to the lesser metatarsals, a sesamoid planing procedure is contraindicated.
Mann and Wapner reported on 14 patients (16 feet) who underwent tibial sesamoid shaving. They noted no functional limitations, and at final follow-up, patients were reported to have a normal range of motion. Excellent or good results were reported in 15 feet. There was one case of recurrent callus formation and four cases of slight recurrence of callosity. The authors reported fracture of the remaining sesamoid as a possible complication, although none occurred.
An isolated excision of a sesamoid can lead to a muscle imbalance of the MTP joint. The development of a hallux varus deformity after fibular sesamoidectomy was noted by Mann and Coughlin, who reported an 8% incidence of hallux varus in a postoperative review.
Nayfa and Sorto reported a 2.2-degree increase in the intermetatarsal angle after tibial sesamoidectomy and a 6.2-degree valgus drift of the hallux after tibial sesamoidectomy. Jahss noted that a wide medial excision of the tibial sesamoid could disrupt the medial MTP joint capsule and lead to a hallux valgus deformity. Likewise, a wide lateral excision with disruption of the adductor hallucis tendon can lead to a hallux varus deformity.
Mann et al. reporting on a series of sesamoidectomies, noted a valgus or varus drift of the hallux in 10% of the patients. Saxena reported varus or valgus drift in 8% of patients after sesamoidectomy. Maintenance of the integrity of the medial capsule and abductor hallucis, when a tibial sesamoidectomy is performed, and maintenance of the integrity of the adductor hallucis and lateral capsule, when a fibular sesamoidectomy is performed, are important in diminishing migration of the hallux postoperatively. After tibial sesamoidectomy, a lateral capsule release, medial capsule reefing, and even a metatarsal osteotomy may be considered if there appears to be an increased risk of a hallux valgus deformity after tibial sesamoid excision.
Mann et al. reported on the surgical excision of sesamoids in 21 patients (average age of 41 years, 66% females). Thirteen tibial and eight fibular sesamoids were excised. Only 50% of patients noted complete relief of pain. Of those who were still symptomatic, 75% noted only occasional or mild symptoms. Sixty percent (12 patients) noted plantar-flexion weakness. One third of the patients noted restricted range of motion. There appeared to be no difference in the postoperative results of tibial or fibular sesamoid excision. In 10% of cases, there was a mild drift of the hallux into either varus or valgus after surgery. Although the subjective level of patient satisfaction was high, the postoperative objective limitations noted were significant.
Lee et al. reported on 20 patients who underwent isolated tibial sesamoidectomy, with an average of more than 5 years follow-up. A meticulous soft tissue closure was performed after the sesamoidectomy, and they reported no change in the hallux valgus or 1-to-2 intermetatarsal angle. Ninety percent of patients were able to resume preoperative activities; however, 30% had difficulty or inability to stand on their tip-toes. They reported a high level of satisfaction at long-term follow-up.
Brodsky reported on 23 sesamoid fractures that went on to chronic non-union. Thirteen medial and 10 lateral sesamoids were involved. The mean time to surgery was 38.8 months. Although 21 of 23 patients had satisfactory results after surgical excision, 2 patients had postoperative weakness of the hallux, 2 had neuropathic symptoms, and 6 had mild-to-moderate pain after surgery. In another study, Brodsky et al. reported on 37 patients (18 male and 19 female) with painful fractured sesamoids that were treated operatively. Avascular necrosis secondary to a sesamoid fracture was observed in 9 patients, 16 were noted to have sesamoid stress fractures, and 12 were related to direct trauma. After surgical excision, the average AOFAS score was 93 points. Several cases of posttraumatic arthritis developed.
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