Trapeziectomy is performed for trapeziometacarpal (TMC) arthritis but decreased lateral pinch strength is a major source of discomfort after the surgery. The magnitude of the decrease is unclear, however, and how the pressure changes in the TMC joint is unknown. To investigate this relationship, we designed a cadaveric study to measure TMC joint pressure using a lateral pinch model, and quantitatively evaluated the effect of trapeziectomy on the pressure measurements. For 10 cadaveric forearms, physiologic forces were applied across the thumb TMC joint by loading five tendons, thereby simulating lateral pinch. Using pressure sensors, we measured the lateral pinch pressure and TMC joint pressure, which averaged 10.1 (range, 4.2-16.2) kg/cm2 and 2.0 (range, 0.8-4.4) kg/cm2 , respectively. A significant correlation between the measurements was found, with an average ratio of 19% (range, 10%-27%). After trapeziectomy and interposition of the tendon ball using flexor carpi radialis, the pressure measurements were repeated under the same conditions. Significant changes were found, which averaged 5.1 (range, 1.7-10.7) kg/cm2 for lateral pinch pressure and 15.0 (range, 5.6-25.6) kg/cm2 for TMC joint pressure. In conclusion, TMC joint pressure could be measured as the ratio relative to lateral pinch pressure using a cadaveric model. After trapeziectomy, the lateral pinch strength decreased, whereas the TMC joint pressure increased.

Numerous arthroplasty techniques had been reported for the treatment of thumb carpometacarpal (CMC) joint osteoarthritis. The purpose of our study is to evaluate long-term clinical and radiographic outcomes of patients who underwent modified trapeziectomy with ligament reconstruction tendon interposition (LRTI).Our retrospective study included 20 consecutive patients with advanced thumb CMC arthritis receiving modified trapeziectomy with LRTI (20 thumbs). For clinical evaluation, we assessed visual analogue scale (VAS), Disabilities of the Arm, Shoulder and Hand (DASH) scores and Kapandji index. Additionally, the grip, pinch power and waist flexion power, radial and volar abduction angle were evaluated, As for radiologic evaluation, we just estimated height of the trapezial space.We took 2-year follow-up. All patients showed decreased VAS from 6.8 preoperatively to 1.4. Mean DASH and Kapandji scores were improved from 52.2 preoperatively to 21.6 and from 6.4 preoperatively to 7.4, respectively. Compared to preoperative range of motion (ROM) for radial abduction and volar abduction, both markedly increased at 2-year follow-up (from 61.2 to 80.1, from 60.6 to 78.3, respectively). Besides, mean power improved from 15.9 preoperatively to 21.7 kg at 2-year follow-up for grip power, from 1.9 preoperatively to 3.5 kg at 2-year follow-up for tip pinch; however, mean waist flexion power showed no significant change from 20.5 preoperatively to 19.7 kg at 2-year follow-up. Notably, there was no significant sinking in height of the trapezial space from 10.0 preoperatively to 9.6 mm at 2-year follow-up. NO case had a complication at final follow-up.Modified trapeziectomy with LRTI treating thumb CMC arthritis in Eaton stage III-IV had a satisfactory efficacy. This new procedure is able to provides enough support for thumb to prevents thumb sinking.

BACKGROUND: Thumb carpometacarpal (CMC) arthritis is a common disease. Various procedures have been described for the treatment of advanced thumb CMC arthritis. This essay shows a CMC arthritis case treated by modified trapeziectomy with ligament reconstruction tendon interposition (LRTI).
METHODS: A 53-year-old Chinese female complained of pain and swelling at the base of the left thumb for 10 years. Visual analog scale (VAS) for thumb was 7 points, Disabilities of Arm, Shoulder and Hand (DASH) score was 51 points, and Kapandji score was 6 points before surgery. Preoperative range of motion (ROM) for radial abduction and volar abduction were 63°and 62°, respectively. Grip power was 15.3 kg and key-pinch power was 1.8 kg before operation. Preoperative waist flexion power was 20.9 kg. Hand x-ray showed left thumb CMC arthritis in Eaton stage III and the height of the trapezial space was 10 mm.
METHODS: She was diagnosed with left thumb CMC arthritis (Eaton III stage).
METHODS: The patient underwent modified trapeziectomy with LRTI. After exposing and removing trapezium, and a hole from the dorsal base to the center of the articular surface was drilled. Then we cut the whole flexor carpi radialis and divided it into 2 halves. Afterward, we passed one-half through the hole and tied it to the other part and sutured them. The rest tendon was then tied continuously and sutured. Then we rolled it up into the space where previous trapezium was located.
RESULTS: Two years after operation, pain and swelling relieved and no recurrence of the clinical symptoms occurred. VAS, DASH, and Kapandji score were 2, 22, 7 points, respectively. ROM for radial abduction and volar abduction were 79° and 78°, respectively. Furthermore, grip power was 22.7 kg and key-pinch power was 3.8 kg. Waist flexion power was 20.0 kg. Hand x-ray showed that the height of the trapezial space was 9.8 mm.
CONCLUSIONS: Modified trapeziectomy with LRTI in treatment of advanced thumb CMC arthritis had a satisfactory efficacy. This new procedure not only prevents thumb sinking, but also provides enough support for thumb.

We performed a retrospective review of 22 thumbs in 22 Chinese patients attending for the basal joint arthritis of the thumb over the last 14 years. There were 16 women and six men with a mean age of 50 years old. All were treated surgically by partial trapeziectomy and volar oblique ligament reconstruction with flexor carpi radialis tendon and interpositional arthroplasty with a free palmaris longus tendon ball after failure of conservative treatment. The mean follow-up time was 48 months. Radiographs did not show any differences in the arthroplasty space index, arthroplasty space, trapezial space ratio and scaphoid-thumb metacarpal distance at the pre-operative evaluation and at the final follow-up evaluation. There was significant difference in the pain score, grip strength, Kapandji score and functional status before and after surgery at final follow-up period. One patient had complex regional pain syndrome which was resolved after receiving a course of anti-inflammatory drugs and physiotherapy. The authors suggest that the modified technique of partial trapeziectomy with tendon interpositional arthroplasty is a safe and effective method in treating basal joint arthritis of the thumb with good short term functional and radiological outcomes and minimal complication.