Comparison between Traditional Suspension and Interposition Arthroplasty with Poly-L,D-Lactide Scaffold in CMC Osteoarthritis

Purpose: The aim of this study is to compare the clinical, radiological, and functional results of an innovative bioreplaceable small joint scaffold for the correction of destroyed small joints in the carpometacarpal joint (CMCj) osteoarthrosis versus arthroplasties at the first CMCj.

Materials and Methods: The randomized, multicenter, parallel-groups study, conducted in collaboration with other European rheumatologic, orthopaedic, and hand surgery teams, is based on the treatment of almost 150 patients recurring to

A poly-l,d-lactide copolymer (PLDLA 96:4) fiber is smelt-spun to 4-ply multifilaments, knitted in a tubular jersey stitch, and the knitted tube is rolled to form a cylindrical scaffold.

The authors performed 40 trapeziectomies following osteoarthrosis of the I CMCj, adding the scaffolds in 20 cases, according to a personal surgical technique, and performing an abductor pollicis longus (AbPL) arthroplasty in the 20 cases of the control group.

At an average follow-up of 10 years we have 12 patients in the scaffold group and 14 patients treated by AbPL arthroplasty.

Outcomes index selected for the study are Jamar and pinch tests, visual analog scales (VAS) for pain and subjective function, Kapandji tests, range of motion (ROM), and X-ray CMCj high maintenance index.

Results: The long-term outcomes studies report better results for the scaffold group than for the control group. X-ray CMCj high maintenance index in the scaffold roup decreased for 25% versus 54% of the control group. Jamar test showed an improvement in strength of 35% versus control group: from 15.7 kg to 21.2 kg in the scaffold group and from 14.8 kg to 14.9 kg in the control group. Pinch test showed an improvemet of 16% in the scaffold group: from 2.77 kg to 3.2 kg in tip pinch and from 4 kg to 4.7 kg in the key-pinch, compared to 2 kg to 2.2 kg and from 3.1 kg to 3.3 kg, respectively, in the control group. More relevant results have been obtained in the VAS scores. In the scaffold group the functional subjective improvment was observed in 60% versus 47% of control group, while VAS pain decreased in 70% of the scaffold group versus 40% of the control group. Kapandji test of control group was unchanged, while in the scaffold group the improvement was seen in 12%.

Conclusions: The joint scaffold for the treatment of first CMCj osteoarthrosis, added to the stabilization technique proposed by the authors, should lead to an enduring interposition tissue, stabilizing the first metacarpal bone, avoiding its proximal migration to the scaphoid, and reducing postoperative tenosynovitis.