Three - five (3 - 5) subjects with Eaton stage III-IV thumb CMC osteoarthritis undergo the basilar joint arthroplasty procedure without using a spacer constructed from human acellular matrix (HADM). Their postoperative DASH scores, grip strength, pinch strength, pain scale scores and quality of life questionnaires are compared to their preoperative scores. These subjects will be compared with a group of twenty-five (25) similar subjects who received the arthroplasty procedure with the use of the HADM spacer.

Twent-five (25) subjects with Eaton stage III-IV thumb CMC osteoarthritis undergo the basilar joint arthroplasty procedure with an interposition arthroplasty technique using a spacer constructed from human acellular matrix (HADM). Their postoperative DASH scores, grip strength, pinch strength, pain scale scores and quality of life questionnaires are compared to their preoperative scores. These subjects will be compared with a group of three - five (3 - 5) similar subjects who received the arthroplasty procedure without the use of the HADM spacer.

A longitudinal dorsoradial incision is made from the base of the first metacarpal to the radial styloid for access to the thumb CMC joint. Trapeziectomy is performed piecemeal using sharp and blunt dissection. The base of the first metacarpal is then decorticated with a sagittal saw. A 4x7 cm sheet of thin FlexHD (HADM) is fashioned by a 4-0 monocryl suture imbrication into the size and shape of the subject's trapezium, keeping the dermal side exposed as much as possible. The allograft is secured with multiple interrupted 3-0 Ticron sutures and the bundle is placed into the post-trapeziectomy space. Additional suture fixation is performed between the FlexHD and the volar capsule of the trapezium, and base of the thumb metacarpal using 4-0 Mersilene sutures. The control treatment group will have the same trapeziectomy but without the placement of the FlexHD acellular dermal matrix.

The objective of this study is to determine whether utilizing HADM will result in increased functionality measured by:

• DASH score
• Pinch and grip strength
• Pain scale
• Quality of life scores and
• Trapezial space on radiographs at designated intervals during the post-operative period