Surface replacement of the wrist is a motion preserving solution for the salvage of a severely destroyed wrist, i.e., a pan-arthritic wrist. Until the early years of the 21st century, the main indication for prosthetic replacement was inflammatory arthritis. Since then, other conditions have increasingly been of interest, including idiopathic degenerative osteoarthritis, posttraumatic arthritis, Kienböck’s disease, and others. There is no clear evidence about which indications lead to the best results and the fewest complications. With the latest generation of wrist arthroplasties the distal carpal row is preserved, onto which the carpal resurfacing component can be fixed. Fixation in the metacarpals is restricted to the index metacarpal. Proximally the radial bone resection is minimal. The implants are mostly metal-on-polyethylene and attempt to mimic the natural anatomy and biomechanics of the wrist and are largely unconstrained. Wrist arthroplasty is a good solution in elderly patients who are not too physically active, or in patients with poor function of the contralateral extremity or other joints of the ipsilateral extremity; in these cases, it may be difficult to compensate for a fused wrist. Generally, clinically and statistically significant improvement in pain scores and patient reported outcome measures are obtained. Most series show no statistically significant improvement of wrist mobility or a statistically significant improvement that is barely clinically relevant. The reported 10-year implant survival ranges from 40–92%. The authors’ experience has led them to revise failed total wrist arthoplasties to total wrist arthrodesis rather than to revision arthroplasties.
Key wordswrist – arthroplasty – replacement – arthritis – implant survival – results
25 Surface Replacement Wrist Arthroplasty
In the past century, two-component implants for total wrist replacement were characterized by extensive resection of carpal bones, bulky implants, and distal fixation in the metacarpals. Failure rates were high and occurred mainly by distal loosening. Implant durability was deceiving and revision surgery was a challenge as a consequence of the resected bone stock. The indications were mainly inflammatory arthritis. On this background, Jay Menon 1 introduced the third generation of total wrist arthroplasty (TWA). He designed a surface replacement prosthesis preserving the distal carpal row, onto which the carpal resurfacing component could be fixed. Proximally, the radial bone resection was minimal. The initial results were favorable, although a high rate of postoperative dislocations necessitated a revision of the implant design. Subsequently, a number of resurfacing prostheses based on the same principles have been developed.
The most commonly reported resurfacing wrist implants are the Universal 2 (Integra), 2 the Re-motion (Stryker), 3 and the Maestro (Biomet). 4 They are characterized by moderate bone resection and avoid fixation in the metacarpal bones, with the exception of an optional, short length of screw fixation in the index finger metacarpal (Fig. 25.1). They attempt to mimic the natural anatomy and biomechanics of the wrist and are largely unconstrained. The prostheses are metal-on-polyethylene, with the radial (proximal) part being concave (metallic in the Re-motion and the Universal, polyethylene in the Maestro) and the distal part being convex. As such, they function similarly to a wrist after proximal row carpectomy. The components are impacted in the bones, mostly without the use of cement. The carpal part is supplemented with screws in the hamate and in the scaphoid/trapezoid/index metacarpal. In recent years, an updated version of the Universal 2 has been launched: the Freedom (Integra). 5 The metal-on-metal Motec (Swemac) 6 could also be considered as a resurfacing implant but differs from the other contemporary designs in being fixated distally in the middle metacarpal and is the subject of Chapter 26.
The Prosthelast (Agromedical) was originally designed as a hemiarthroplasty and has now been extended to a TWA. The fixation of its carpal component is based on sagittal screw fixation in the capitate. 7
25.3 Indications and Contraindications
Surface replacement of the wrist is a motion-preserving solution for the salvage of a severely destroyed wrist, i.e., a pan-arthritic wrist. For patients with scapholunate advanced collapse (SLAC) II or III wrists, with preserved cartilage in the midcarpal or radiolunate joints, other interventions should be considered, such as a proximal row carpectomy or a four-corner arthrodesis. 8 In cases of an irreparable joint surface of the distal radius in elderly low-demand patients with an intra-articular distal radius fracture, radiocarpal arthrodesis or distal radius hemiarthroplasty can be used.
Until the early years of the 21st century the main indication for prosthetic replacement was inflammatory arthritis. Since then, other conditions have increasingly been of interest. 9 Today, the debate over indications is polarized between the rheumatoid wrist, generally in low-demand patients but with poorer bone stock, and idiopathic or posttraumatic osteoarthritis (OA)—those patients generally having better bone stock but also being more physically active. There is no clear evidence about which indications lead to the best results and the fewest complications: it seems that carefully selected patients with rheumatoid arthritis (RA) or OA do equally well. 9
Generally, surgeons should be very cautious about offering TWA to young patients ≤50-year-old) (especially for OA), patients that do heavy or moderately heavy work, patients with poor bone quality, rheumatoid patients with severe wrist instability, and patients with poor compliance. In these cases, total wrist arthrodesis is a better option. Conversely, TWA is a good solution in elderly patients who are not too physically active, or in patients with poor function of the contralateral extremity or other joints of the ipsilateral extremity: in these cases, it may be difficult to compensate for a fused wrist.
When advising patients of the options, they should always be given exhaustive and transparent information on what they can expect in terms of complications, function, and durability of TWA as well as of the other available surgical solutions; the choice of operation must be based on shared decision-making.
It seems that the use of TWA has been declining in the past decade for several reasons 10 : primarily, the number of severely destroyed rheumatoid wrists has declined due to the success of new disease-modifying drugs; the initial enthusiasm created by the promising early and medium-term results has been moderated by some longer term reports; and hemiarthroplasty has taken over some of the indications.
25.4 Results in the Literature (Short Version)
Early Postoperative Complications
The rate of deep postoperative infections is reported to be very low with current implant techniques including the use of perioperative antibiotics. Instability with dislocation was common with the first version of the Universal implant but this problem has been solved with the modified versions, the Universal 2 and the Freedom, and has not been a major problem with the Re-motion or the Maestro. 11 In the systematic review of the literature from 2009 to 2013, 12 the other early complications reported in the literature are: 3 to 17% wound problems; 5 to 14% superficial infection; 4% synovitis; 3 to 5% tendon laceration/rupture; 3 to 9% nerve problems. These complications are similar to those encountered after partial and total wrist arthrodesis. Gaspar et al 13 reported a rate of complications as high as 57% after TWA with the Maestro.
Osteolysis and Implant Loosening
Focal periprosthetic radiolucency after resurfacing arthroplasty of the wrist, with or without frank loosening of the components, has been reported repeatedly. 6 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 Radiolucency is the radiographical sign of periprosthetic osteolysis. In most cases, it is confined to the extremity of the implant components near the joint space and is less than 2 mm in width. In some instances it enlarges initially but stabilizes after a few years without implant loosening (Fig. 25.2). In other cases it results in subsidence, mostly of the carpal components. 15 The mechanism causing osteolysis is multifactorial, including micromotion, particulate debris-induced bone resorption, stress shielding, and increased intra-articular pressure. While it is not clear how to treat asymptomatic-limited periprosthetic osteolysis, osteolysis associated with pain typically requires revision of the implant components or conversion to a wrist arthrodesis.
25.4.2 Functional Results
Generally, clinically and statistically significant improvement in pain scores and patient-reported outcome measures (PROMs) such as the Disability of the Arm, Shoulder and Hand (DASH) questionnaire, the Patient-Rated Wrist Evaluation (PRWE) questionnaire, and the Lyon wrist score can be expected after TWA. 11 , 12 , 22 , 24 , 25 These scores are comparable to the scores obtained after total wrist arthrodesis, although exact comparison is difficult due to the lack of controlled studies. Most series show no statistically significant improvement in postoperative ranges of motion or a statistically significant improvement that is barely clinically relevant. 3 , 4 , 14 , 18 , 22 , 23 , 26 27 , 28 Reigstad et al reported significantly improved ranges of motion with the Motec prosthesis from 97 to 136 degrees (extension + flexion + ulnar + radial). 6 Changes in grip strength are difficult to evaluate in the published literature but a modest improvement is reported in some series. 12 , 22 , 25
25.4.3 Implant Durability
Implant durability is best assessed with a cumulative survival analysis according to the Kaplan-Meier method with “revision of implant components” as the criterion for implant failure. Alternatively, the revision rate may be used but the revision rate is almost always time dependent, i.e., increasing with increasing implant longevity. Reports are equivocal (Table 25.1).