Hallux Rigidus & Silastic Total Implants JOSHUA L. MOORE, DPM FACFAS ASSISTANT DEAN OF EDUCATIONAL AFFAIRS TUSPM CLINICAL ASSISTANT PROFESSOR OF SURGERY
Definitions Hallux Limitus 1 st MTPJ range of motion less than 65 degrees in the sagittal plane. Hallux Rigidus - Absent motion of the 1 st MTPJ *Normal gait requires 65-75 degrees of dorsiflexion.
Definitions Functional: Decreased 1 st MTPJ motion when foot loaded or in functioning position. Responds well to orthosis Structural: Decreased hallux motion while foot is loaded or unloaded.
Etiology Long 1 st ray 1 st Ray elevatus Hypermobile 1 st ray DJD Septic arthritis Systemic arthridities Weak or absent peroneus longus Iatrogenic Trauma Neoplasms
Presentation Pain to joint with palpation & ROM Palpable exostosis 1 st ray elevatus Callus plantar IPJ Metatarsalgia Bursitis to 1 st MTPJ
Radiographic findings Flattening of 1 st met head Dorsal exostosis Loose bodies Joint space narrowing 1 st metatarsal elevatus
Conservative treatments NSAIDS Injections Physical therapy modalities Orthosis Morton s extension, 1 st ray cut out
Surgical considerations Joint salvage Reserved for limitus Excision of ossicles/exostosis Joint destructive
Implants Interpositional implant Resection arthroplasty with placement of spacer Total joint replacement Benefits Total resurfacing and joint replacement Immediate weight bearing usually allowed Maintain some function Typically less healing time Room for other procedures in the future
Implant Indications/Goals Indications Hallux Rigidus Crepitus & pain with ROM Revisional Surgery Systemic arthridities DJD Osteochondral fractures Goals Reduce pain Gain/Restore motion Correct deformity Long term results Maintain stability
Total Implants Hinged silastic Maintains position, stability and motion >30 years of successful clinical outcomes May use grommets to prevent implant breakdown and erosion
Pre Op Considerations Patient awareness!! May break down and need replaced or require fusion May have a dull pain May not gain much motion Does the patient have adequate bone stock? Normal alignment of 1 st ray (sagittal and frontal planes) Length of lesser metatarsals
Complications Infection Lack of hallux purchase Painful/limited ROM Fracture of metatarsal &/or phalanx Loosening of prosthesis Metatarsalgia Stress fractures lesser metatarsals Interference of sesamoid position and gliding
Complications Foreign body reaction Osteolysis Implant destruction Ectopic bone formation Chronic edema Subchondral cysts Telescoping of bone
Complications Infection Normally 10 5 whereas with an implant it is 10 2 Reported infection rates from 1-2% Do not let pain and inflammation fool you. Implant destruction Fatigue fracturing implant fractures due to fatigue Breakdown caused by cutting or modifying implant. Subchondral cyst formation 75% of all patients Only problematic if fracture or collapse
Complications Reactive synovitis and metallosis Dendritic synovitis!!! Giant cell & inflammatory reaction to silicone. Microfragments formed through abrasion of bone on implant Often require implant removal Ectopic bone formation Bony proliferation around implant Cause limited & painful ROM
Pearls Minimal incision for reduced adhesions and scarring dorsally Use of rotary burr to prepare medullary canal Remove a small plantar wedge from metatarsal head Do not touch the implant with your hands Do not cut or compromise the implant Begin immediate weight bearing and ROM exercises Resect as little bone as possible
References Morgan S, Ng A, Clough T. The long-term outcome of silastic implant arthroplasty of the first metatarsophalangeal joint: a retrospective analysis of one hundred and eight feet. Int Orthop. 2012 Sep;36(9):1865-9. Sullivan MR. Hallux Rigidus: MTP Implant Arthroplasty. Foot Ankle Clin. 2009 Mar;14(1):33-42. Brage ME, Ball ST. Surgical options for salvage of end-stage hallux rigidus. Foot Ankle Clin. 2002 Mar;7(1):49-73. Bonet J, Taylor DT, Lam AT, Williams E, Keane LA. Retrospective analysis of Silastic implant arthroplasty of the first metatarsophalangeal joint. J Foot Ankle Surgery. 1998 Mar-Apr;37(2):128-34. Lemon B, Pupp GR. Long-term efficacy of total SILASTIC implants: a subjective analysis. J Foot Ankle Surgery. 1997 Sep-Oct;36(5):341-6.