Trapeziometacarpal prostheses, along with trapeziectomies and interposition arthroplasties, are one of the modern surgical options for the treatment of trapeziometacarpal osteoarthritis. The short-term and medium-term results have been improved by modifications of the initial models (modularity, anatomic stems, bony fixation, surgical technique) and their indications have now been extended. The level of complications is acceptable for many of the models. Dislocations are uncommon (single and double mobility principle). The future improvements will focus on durability of polyethylene and bony fixation of the trapezial cup. Indications are actually based on the level of activity of the patient, and radiological aspect of the osteoarthritis and the trapezium.
Key wordstrapeziometacarpal osteoarthritis – surgical treatment – prosthesis – arthroplasty
21 Total Thumb CMC Arthroplasty
Osteoarthritis of first carpometacarpal (CMC) joint is the second most common location of degenerative arthritis of the hand. 1 It is in fact a regional condition, with consequences on the constitutive elements of the thumb: metacarpophalangeal (MCP) joint, extensor and flexor tendons, tendons of the first compartment, muscles of the first web, carpal tunnel. It may create instability of the first column with different consequences: functional (pain), biomechanical (strength), anatomical (mobility), and esthetic (Z-deformation). First treatment is conservative, and surgical procedure is only proposed in case of failure. Indications are then high level of pain, decrease of strength (key-pinch, grasp), stiffness of the first ray, and sometimes esthetic aspect (Z-deformation). Trapeziectomy and arthrodesis of the CMC joint were the first procedures to be proposed, 2 , 3 followed by several modifications of trapeziectomy, such as tendon interposition, chondrocostal interposition, and ligamentoplasty (abductor pollicis longus [APL], flexor carpi radialis [FCR] tendons). CMC arthrodesis causes significant decrease in mobility and high level of complications. 4
Outcomes of the different trapeziectomy procedures are generally reliable, but with some drawbacks (irreversible osseous resection, shortening of the thumb, Z-deformation, intracarpal instability, delay of recovery, low strength). In early cases of osteoarthritis, with dysplasia of the trapezium, different types of osteotomy have been proposed, with long-term good results.
For better preservation of length of the first ray, two other types of surgical procedure have been more recently introduced: interposition implants and coupled prosthesis. Implants may be associated with partial (resurfacing) or total (interposition spacer) trapeziectomy. Most of them are now made of pyrolytic carbon, with a compatible module of elasticity and optimal wear resistance. 5 Instability of some types of these implants 6 limits their indications.
Total trapeziometacarpal joint “ball-and-socket” prosthesis was proposed in the early 1970s. The aim is to give a stable fulcrum between trapezium and first metacarpal, allowing conservation of centers of rotation of the joint for optimal muscular action, and conservation of length of first ray.
21.2 Historical Aspects
Jean-Yves de la Caffinière, 7 a French orthopaedic surgeon, designed in 1971 (Fig. 21.1), and published in 1973 the first total CMC 1 prosthesis, based on the principle of “ball-and-socket.” This prosthesis was made of chromium-cobalt alloy, cemented with a straight neck, straight stem, polyethylene cup, and single size. First results are disappointing, with high levels of loosening of the cup. 8 Modification of this first implant was made and results published by de la Caffinière. 9 Long-term results were good 10 , 11 , 12 or moderate, 13 limiting the use of this prosthesis in elderly low-demanding patients. In 1982 Braun analyzed the results of 29 “Braun-Cutter” implants and later Badia and Sambandam 14 reviewed 26 cases with good results, recommending this technic for low-activity-demanding old patients. Then a second generation of ball-and-socket prosthesis appeared in the 1990s, with modifications in the design and fixation. Some types were evolution of same initial implants (GUEPAR); others were modifications of other initial implants (Maia, modification of initial Arpe, Isis evolution of GUEPAR II). Some of them disappeared due to commercial failure or high level of complications. 15 , 16 , 17 , 18 , 19 Although a number of reports were made by the original conceptors, there were few cases and few prospective analyses, making the analysis of these different implants difficult. Then long-term follow-up of some of these prostheses 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 allowed accurate choice of the implants, and were followed by ultimate modifications (semiretentivity, double mobility) in the concept of the prosthesis (Fig. 21.2).
Actually most of the main models are native from Europe, especially from France, explaining the important differences between the rules of hand and orthopaedic surgeons in surgical treatment of CMC 1 arthritis. Trapeziectomy (with or without ligament reconstruction and tendon interposition [LRTI]) remains the commonest surgical option for the majority of American surgeons, and only 2% of them do prosthesis, 28 whereas the number of CMC prosthesis is between 2 and 3.5 times higher than trapeziectomy in French and Belgian hand surgeon population (Fig. 21.3 and Fig. 21.4).
21.3 Different Types of Total CMC Arthroplasty (TCA)
The implants used actually are essentially based on the “ball-and-socket” principle, for replacement of the “approximate center of rotation” of normal TM joint. 29 , 30 Most of them get the center of rotation in the trapezium; in one type (Rubis II) the center is in the base of the first metacarpal. The “ball-and-socket” principle is a simplification of normal anatomical kinematics (nonintersecting and nonorthogonal rotation-axes). Unlike the different technics of trapeziectomy, biomechanically the TCA restores the point of support between the trapezium and the first metacarpal, and anatomically respect most of bone, tendons, and ligaments of the thumb.
The goal of TCA is to restore strength, range of motion, and remove pain.
Huang et al 18 analyzed 19 types of TCA, corresponding to evolution of initial conceptions, drawings, changing of fixation, and apparition of modularity. Certain types of TCA have disappeared due to bad results or commercialization problems.
Actually, most of TCA get anatomical design of the stem, with several sizes, several types of neck (length, orientation), several sizes and shapes of cup (hemispherical, cylindro-hemispherical, conical, truncated, screw), and modular construction (stem, neck, cup, insert of Polyethylene [PE]). Most of the types have a metal-polyethylene couple, some metal-on-metal couple. Some models propose semiconstrained couple, for improving stability of the prosthesis. Osteointegration after press-fit insertion is achieved by covering of cup and stem with hydroxyapatite (HA) or porous coating. Some models propose fixation with cement, in first intention or for revision.
Last modifications are applications of the principle of double-mobility, inspired by the hip prosthesis, on the TCA (Moovis, Touch), for improving stability and decreasing the shear forces between the cup and the bone trapezium.
21.3.1 The Models (Table 21.1)
Elektra 31 is modular, unconstrained, uncemented arthroplasty. Its metacarpal component is a HA-coated titanium stem (four sizes) with chrome-cobalt head and neck (four sizes). The cup (diameter 6.5 mm) is a chrome-cobalt cone-shaped press-fit screw (one size).
Motec (Swemac AB) 32 is unconstrained, uncemented arthroplasty. The stem is a threaded, slightly conical component (four sizes), coated with Bonit. Trapezium is also threaded with HA-coated surface (one size).
Rubis I and II 21 is an unconstrained reverse prosthesis (center of rotation in the base of the first metacarpal), coated with microporous titanium by plasma torch. Triangular section of the stem. Range of motion: 55 degrees in all directions. Trapezial cup is a screwed circular plate.
de la Caffinière 7 : Chromium-cobalt alloy (Vitalium), cemented with a straight neck, straight stem, polyethylene cup, and single size.
Ledoux/Carrat 33 : Conical cup with six wings, expanded by cylindrical polyethylene liner, producing a “plug” effect and immediate anchorage. Anatomic stem. Arc of mobility is 66 degrees.
Braun-Cutter 14 : Cemented, cylindrical outer shape PE cup and titanium conical stem implants (one size). Arc of mobility is 90 degrees.
Roseland 26 : Semiconstrained noncemented implant with tronco-conical cup (two sizes) and T-shape stem (three sizes), coating with HA in its proximal part. Not commercialized anymore.
Arpe 20 , 23 , 27 : Uncemented titanium cup and stem. Modular, straight, and offset neck; two head length; stem (four sizes). The cup is hemispherical, HAP-coated (two sizes, 9 and 10 mm), and the liner PE may be retentive or not retentive. Arc of mobility is 120 degrees.
Ivory 22 , 34 : Anatomical HA-covered metal stem, double-coned HA-covered cup, with PE (ultra-high molecular UHMPE) insert. The cup presents a double taper, for stable press-fit. Fixation of the neck on the stem in three rotations (−30, 0, +30 degrees). Cup and PE are separate. Arc of mobility is 91 degrees.
Isis 35 , 36 : Evolution of the Guepar. Titanium stem, triangular, porous coated in its proximal part (five sizes); modular neck with variable length and orientation; semiretentive cup. Arc of mobility is 68 degrees. Two types of cup: cemented (two sizes), screw (one size).
Maia 24 , 25 , 37 : Semiconstrained or unconstrained ball-and-socket implant, with anatomical triangular stem (four sizes), removable PE insert, hemispherical cup (two sizes), two types of neck. Arc of mobility is 110 degrees.
Moovis: Double mobility principle, with short triangular stem (three sizes), and conical cup.
Touch: Double mobility principle, neck with inclination of 15 degrees to counteract the horizontal stress of dorsoradial subluxation of certain types of osteoarthritis, and decrease the stress on the trapezium cup.
MojeAcamo: Based on the principle that ceramics have the least amount of wear, and a low friction joint interface. Total ceramic implant, uncemented, coating is a glass-ceramic layer, 19 and osteointegration at the interface bone/implant is favored by roughened surface.
Another type of TCA is based on resurfacing prosthesis, duplicating the double-saddle anatomy of the normal joint.
Camargue: Trapezial implant with saddle shape, and PE insert with saddle shape attached to the stem. Not commercialized since 2005.
SR TMC (Avanta, San Diego, CA, USA): PE metacarpal short stem and trapezium component of chrome cobalt. 38
21.4 Surgical Technique
The “approximative” center of rotation has to be restored as far as possible during surgery. The orientation of the cup is important for prevention of eccentric wear of PE, instability of the stem, and ideal physiological range of motion of the prosthesis. 39 , 40
21.4.1 Surgical Approaches for TCA
Posterolateral or Lateral (Fig. 21.5)
The incision is longitudinal (3–5 cm), distal to the first tendinous compartment (abductor pollicis longus [APL] and extensor pollicis brevis tendons) (Fig. 21.1). After visualization of sensitive branches of anterior and dorsal radial nerve, the approach of trapeziometacarpal joint may be of three types: longitudinal, with a proximal capsulo-ligamentar flap, or with L-shape flap. Important steps are the section of the intermetacarpal ligaments, the resection of medial osteophyte and anterior calcifications, synovectomy, and optimal exposure of the trapezium surface. Advantages of this approach are the conservation of insertions of thenar muscles and the quality of closure. Disadvantage is the technically demanding exposure of trapezium surface, especially in male-centered arthritis with strong ligaments.
It is a modification of the Gedda-Moberg approach without the proximal incurved branch. After dissection of the sensitive branch of anterior radial nerve, a deinsertion of the APL tendon and the proximal insertions of lateral thenar muscles are done, then two capsulo-ligamentar flaps are elevated for optimal exposure of the joint. The main advantage of this approach is the best exposure of trapezium surface.
21.4.2 Steps for Insertion
Whatever the model of prosthesis and the surgical approach, the quality of results depends on few essential points. First of them is the maximum shortening of the learning curve, which means exercises on cadaver pieces before first case, and to be helped during the first case by a senior surgeon. Then respect the following points:
Optimal exposure of trapezium surface.
Section of intermetacarpal ligaments.
Resection of medial trapezial osteophyte.
Optimal centering and orientation of the cup.
Intraoperative fluoroscopic control.
Reinsertion of APL tendon to the APB muscle, or on the base of the first metacarpal, to minimize the risk of dislocation.
Testing of stability of prosthesis in all sectors of mobility (research of “came-effect”).
Testing of tension: not too tightened to allow mobility and decrease stress on the components, and not too loose to prevent instability. Allow a piston-effect of less of half of the head.
21.4.3 Postoperative Care
Immobilization of the thumb is the rule with cast or splint for a mean period of 3 weeks, but some surgeons authorize early return of light activity of the thumb with protection by removable splint. Rehabilitation may be done after this first period, to reinforce the extrinsic and intrinsic muscle groups, but usually the patient is asked to do the exercises himself. The delay for functional recovering of the thumb is variable, around 10/12 weeks after surgery.
The results of the CMC joint total arthroplasties depend on the satisfaction of the patient, the objective clinical results (pain, strength, mobility, esthetic aspect), radiological modifications, and the level of complications and revisions.
21.5.1 Results of the Prosthesis
First TCA have been inserted more than 45 years ago, and during this period, there have been good and bad results. 16 , 18 , 31 , 41 Bad results with unacceptable high level of failure for certain types of prosthesis, essentially metal-on-metal articulations, 15 , 16 , 17 some material (ceramic), 41 , 42 and these models have been abandoned because of these known poor results. 15 Actually, main types of TCA have been followed with long-term follow-up, 20 , 21 , 22 , 24 , 26 and their results are acceptable with high level of satisfaction of the patients.
21.5.2 Comparison with Trapeziectomies
Few analysis compared the two technics. In each of these comparisons the results are better for the prosthesis: strength and delay of recovery, 12 , 43 , 44 , 45 , 46 , 47 mobility, 47 Q-DASH, and esthetic aspect. 47
21.5.3 Complications (Table 21.2) Complications related to the prosthesis
Related to the Prosthesis
Some complications have almost disappeared: related to the stem (anatomical stem), fracture of the trapezium (best ancillary), related to cement fixation (press-fit/HA/porous-coated fixation). The main problems are localized around the cup: failure of fixation (radiolucent lines/loosening, tilting, subsidence), 52 wear of PE, and dislocation (Fig. 21.6 and Fig. 21.7). The problems of fixation are various: mechanical properties of the material (elasticity), quality of bone in trapezium, quality of osteointegration, level of stress at the interface bone/cup (level of activity), design of the cup, and quality of positioning of the cup at implantation. Wear of PE is frequent after several years, depending on the quality and the thickness of material, but also by penetration of the cup by head of prosthesis. 48 Double mobility and modification of PE (cross-linked) should decrease the incidence of this problem. Dislocation may occur early, due to traumatism or technical error: orientation of the cup, cam-effect with medial osteophyte. Dislocation may appear after several years, related to wear of PE and instability.
De Quervain tenosynovitis is frequent with certain series, related to excessive tension of the implant.
Elevated serum chrome and cobalt values for patients with metal-on-metal articulation (Elektra, Motec), without being a general health risk. 41