Union Rate, Metalwork Removal and Complications in Lapidus Bunion Correction using a Plantar Lapidus Plate, Intercuneiform Stabilisation and Immediate Weightbearing

Research Type: Level 4 – Case series Introduction/Purpose: The Lapidus procedure aims to correct Hallux Valgus deformity in three planes by performing a corrective 1st tarsometatarsal joint (TMTJ) fusion, distal lateral soft tissue release, medial eminence resection +/- Akin osteotomy. Traditionally the fusion site is stabilised with screws and/or medial or dorsal plates and immobilised non-weightbearing in a plaster cast or orthotic boot with weightbearing commenced from six weeks. The procedure has been associated with non-union rates of 10% or higher. The procedure has been criticised for shortening of the 1st metatarsal. Recurrence of Hallux valgus has been observed with intercuneiform diastasis. Methods: Between July 2021 and June 2024, 24 consecutive Lapidus procedures were performed by the senior author utilising low-velocity, length retaining joint preparation, fixation with a plantar Lapidus plate and a screw from the first metatarsal base to the middle cuneiform with immediate weightbearing allowed in a heel weightbearing shoe and/or short orthotic boot. Radiographs were obtained at 6 weeks, 12 weeks, 6 months and 12 months. Radiographic union & correction (IMA, HVA, DMAA, sesamoid station, metatarsal head shape & 1st:2nd Metatarsal ratio), requirement for metalwork removal and complication data were recorded prospectively. Results: All cases achieved radiographic union by 12 weeks assessed on radiographs and clinically (90% confidence of < 10% non-union). Pre-operative mean IMA, HVA & DMAA were 17.97, 40.97 and 27.63 respectively with a mean 1st:2nd metatarsal ratio of 99.49%. Post-operative mean IMA, HVA & DMAA were 7.48, 14.44 and 8.55 respectively with a mean 1st:2nd metatarsal ratio of 99.89%. In one case, superficial wound erythema was observed which resolved with oral antibiotics. In one case, the plate/screw construct was exchanged for an intercuneiform screw due to irritation of the 2nd TMTJ by the 1st metatarsal base-middle cuneiform screw. There were no cases of Tibialis Anterior or Peroneus longus tendon irritation or rupture. There were no cases of transfer metatarsalgia. There were no cases of Thromboembolic events. Conclusion: The Lapidus procedure is criticised for concerns about non-union, 1st metatarsal shortening and the requirement for prolonged immobilisation. Utilisation of a plantar plate for fixation of the 1st TMTJ is criticised for the potential to cause irritation or damage to the Tibialis Anterior and/or Peroneus Longus tendons. Intercuneiform diastasis has been suggested to cause recurrence. In our series, we demonstrate that the Lapidus procedure can be performed safely using a plantar plate and immediate weight-bearing with low non-union rates, retention of 1st metatarsal length and reliable IMA, HVA & DMAA correction with no tendon irritation and low hardware removal rates.