Interventional procedure overview of synthetic cartilage implant insertion for first metatarsophalangeal joint osteoarthritis (hallux rigidus)

General

In an RCT of 219 patients, the rate of any adverse event was 69% in the implant group and 72% in the arthrodesis group (p=0.727). For any serious adverse event, the rates were 20% and 18%, respectively (p=0.999) (Baumhauer, 2016).

Pain or inflammation

Serious pain at the implant site was reported in 5% (5/112) of patients in a case series of 119 patients. All 5 patients had the implant removed and conversion to arthrodesis, as described in the efficacy section (Glazebrook, 2019).

In a case series of 60 patients (64 implants), 30% (19/64) of implants had advanced imaging workup after the procedure. This was for continued pain, inflammation and further evaluation of the implant and surrounding structures (mean 12 months follow up, range 3 to 30 months). MRIs showed residual capsular inflammation in all patients, bone marrow oedema of the proximal phalanx or metatarsal in 18 patients, and degenerative changes or inflammation at the metatarsosesamoid articulation in 7 patients (Cassinelli, 2019).

In a case series of 16 patients (18 implants) who had postoperative MRI for persistent pain or dysfunction, 78% (14/18) of implants had evidence of fluid around the implant, and all implants had oedema in the bony proximal phalanx, metatarsal and soft tissues (mean follow up 13 months) (An, 2020).

Joint pain and stiffness were reported in 60% (12/20) of patients at 6 months in a case series of 20 patients. This was treated by manipulation under anaesthesia with an intra-articular corticosteroid injection. Swelling was reported by 10% (2/20) of patients. At 12 months, the rate of joint pain and stiffness was 25% (5/20). Transfer metatarsalgia was reported in 1 patient in the same study (Harmer, 2020).

Persistent pain was reported in 12% (7/60) of patients who had cheilectomy and Moberg osteotomy with a synthetic cartilage implant and 11% (8/73) of patients who had cheilectomy and Moberg osteotomy without an implant, in a non-randomised comparative study of 133 patients. This was treated by steroid injections, orthotics or shockwave therapy (Chrea, 2020).

Infection

Infection was reported in 1 patient in the case series of 119 patients. The patient had implant removal, sinus debridement, and removal of tissue from the first metatarsophalangeal (MTP) joint at about 36 months of follow up. A Staphylococcus aureus infection was confirmed (Glazebrook, 2019).

Infection needing antibiotics was reported in 5% (3/60) of patients who had an implant inserted and no patients who had cheilectomy and Moberg osteotomy without an implant, in the non-randomised comparative study of 133 patients (Chrea, 2020).

In a review of the FDA MAUDE database, there were 4 reports of infection associated with synthetic cartilage implant insertion. The implant was removed in 3 patients, 2 of whom had an antibiotic spacer inserted. One patient had oral antibiotics (Metikala, 2020).

Component loosening or subsidence

In the review of the FDA MAUDE database, there were 16 reports of subsidence associated with synthetic cartilage implant insertion. A secondary procedure was described in 11 of the 16 reports, including 6 conversions to fusion (Metikala, 2020).

In the case series of 60 patients, 1 patient had subsidence of the implant below the cortical bone of the metatarsal head with resultant bony contact between the proximal phalanx and metatarsal head. The patient had implant removal and conversion to fusion. In the same study, a second patient had revision for continued pain, inflammation, and suspected implant subsidence. The implant had subsided and was damaged, and pathology was consistent with foreign body giant cell reaction and neovascularisation. A bone mineral density scan showed that the patient had osteopenia (Cassinelli, 2019).

Component fracture

In the review of the FDA MAUDE database, there were 9 reports of 'fragmentation' associated with synthetic cartilage implant insertion. Three implants were removed, there were 2 revisions to an unspecified implant, 1 implant was removed and replaced with another synthetic cartilage implant, 1 was converted to first MTP joint fusion, 1 had the fragmented portion replaced and the same device reimplanted, and 1 had an unknown outcome (Metikala, 2020).

Bony reactions

Bony reactions were reported in 50% (48/97) of patients after a mean follow up of 5.8 years in the case series of 119 patients. These reactions included erosion (2%), cystic changes (21%), loss of cortical margins (25%) and osteolysis (2%) (Glazebrook, 2019).

In the review of the FDA MAUDE database, there were 3 reports of erosion associated with synthetic cartilage implant insertion (Metikala, 2020).

Other

Intraoperative metatarsal fracture during insertion of the implant was reported in 1 patient in the case series of 103 patients. This was treated at the time with open reduction and internal fixation (Eble, 2020).

Severe erosive wear of a synthetic cartilage implant 2 years after implantation was described in a case report. The patient needed a lengthening arthrodesis to correct malalignment (Reddy, 2021).

Anecdotal and theoretical adverse events

In addition to safety outcomes reported in the literature, professional experts are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never happened).

For this procedure, the professional experts did not describe any additional anecdotal or theoretical adverse events.