Primary endoprosthetic replacement of the arthritic CMC-1 joint

Effective shape of ball-and-socket prosthesis in restoring range of thumb motion for total thumb carpometacarpal joint arthroplasty: three-dimensional motion analysis

PURPOSE

Total joint arthroplasty (TJA) has often been used to treat thumb carpometacarpal (CMC) osteoarthritis (OA). However, guidelines for the CMC prosthesis shape remain unclear. This study aimed to identify the effective shape of a ball-and-socket prosthesis in restoring the range of thumb motion after TJA.

METHODS

The participants were 10 healthy young adult men (22-32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD.

RESULTS

We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values.

CONCLUSION

Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis.

Basal thumb arthritis surgery: complications and its management

The management of complications after surgery for basal thumb arthritis is sometimes challenging, and there are no clear recommendations on how to evaluate and manage patients with residual symptoms. The aim of the present article was to review the most common complications after surgery for basal thumb arthritis, with an emphasis on resection arthroplasty, joint replacement and joint fusion. In addition, possible management strategies for the different types of complications will be highlighted.

[Arthroplasty of the hand and wrist]

Arthrosis and autoimmune arthritis frequently lead to major impairment of hand function. Primary therapy consists of well- tried conservative treatments and joint preserving surgical options for special indications. In advanced stages silicon spacers remain the gold standard surgical option for replacement of proximal interphalangeal and metacarpophalgeal joints of the fingers. Alternatively, surface replacement prostheses can restore the biomechanical properties of these joints more porperly. In case of the carpometacarpal (CMC) joint of the thumb, arthroplasty is gaining popularity as modern implants show excellent mid-term outcome. Although current forth generation implants for wrist replacement are promising, total wrist arthroplasty is currently reserved for exceptional indications.

Scaphotrapeziotrapezoid joint loading during key pinch grip before and after trapeziometacarpal arthroplasty: a cadaver study

In a previous cadaver study, we directly measured the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces. We noted that the joint load ranges from 2 kg to 4 kg during progressively greater key pinch from 0.5 kg to 1.5 kg. Using the same experimental approach, the aim of the current study was to measure and compare the load acting on the scaphotrapeziotrapezoid joint for the same levels of isometric key pinch force, and how it changes after trapeziometacarpal arthroplasty. We performed a cadaver study using 7 fresh-frozen, unembalmed adult forearms and hands (2 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). Before the trapeziometacarpal joint surgery, median load values recorded in the scaphotrapeziotrapezoid joint were 1.2 kg (IQR, 1.0-1.4), 1.6 kg (IQR, 1.6-2.5) and 2.4 kg (IQR, 2.3-3.4) during 0.5 kg, 1 kg and 1.5 kg key pinch, respectively. After the trapeziometacarpal arthroplasty, median joint contact forces did not change significantly relative to the original configuration. Our findings indicate that the loads measured in the scaphotrapeziotrapezoid joint during a simple key pinch are in fact lower than those measured inside the trapeziometacarpal joint. After trapeziometacarpal arthroplasty, the values are similar with no increase in load, suggesting that clinically asymptomatic scaphotrapeziotrapezoid radiographic involvement may not be a contraindication to arthroplasty.

Total joint replacement for osteoarthritis of the carpometacarpal joint of the thumb: why and how?

Total joint replacement has certain advantages over other surgical treatment methods for osteoarthritis of the thumb carpometacarpal joint, including restoration of thumb length and alignment, good cosmetical result, fast recovery of hand function and prevention of iatrogenic complications at neighbouring joints. Disadvantages include the technical difficulty to perform this surgery and a possible higher complication rate. A meticulous surgical technique is mandatory. Combined with a cementless and modular ball-in-socket implant with a metal-on-polyethylene friction couple, a 10-year survival rate higher than 90% can be expected. Revision surgery is possible with implant exchange or conversion to trapeziectomy.

[Resection arthroplasty for thumb basal joint arthritis]

Due to the crucial role of the thumb for gripping, osteoarthritis of the first carpometacarpal joint leads to a substantial impairment of hand function. There are effective nonoperative and joint-preserving surgical treatment options for early stages of the disease. In advanced cases, after exploiting conservative treatment, carpometacarpal thumb arthrodesis or arthroplasty may be indicated in selected cases but trapeziectomy with or without interposition or suspension constitutes the gold standard surgical procedure. This reliably provides favorable results, irrespective of the technique, with pain relief, good physical function, excellent patient global assessment and low complication rates.

[Experiences with arthroplasty of the basal joint of the thumb : The"mini-hip" gains ground]

The complex kinematics of the saddle joint has been a challenge in the development of trapeziometacarpal prostheses. The introduction of the dual-mobility design increases the range of motion and limits strains on the cup fixation. Therefore, rates of loosening and dislocation have been markedly reduced. Furthermore, several studies showed a similar relief of pain, range of movement and grip strength compared to the results of resection arthroplasty. The preservation of the length of the first ray as well as the more stable and functional joint can be favourable in younger and active patients. Further investigation is needed to determine whether or not those higher demands affect long-term survivorship. The high grade of patient satisfaction, the shorter recovery time and the safe surgical technique motivates considering the implantation of a total endoprosthesis with a dual-mobility cup as an attractive alternative to resection arthroplasty in the operative treatment for trapeziometacarpal osteoarthritis.