The Theory of Environmental Deformity (TED) describes a series of definitive events explaining unique common characteristics in over three hundred hands diagnosed with Carpal Tunnel Syndrome (CTS). The most intriguing of many arthrokinematic anomalies in CTS is the inauspicious involuntary drop of the carpus. Measuring Carpal Transmission Forces (CTF) during hand activity revealed intra-carpal pulley forces high enough to explain the volar carpal drop observed in all patients with CTS. Histology changes in the carpal contents, deforming distribution of forces on the retinaculum and intracarpal ligaments may result from increased CTF and may be present in other joint tunnel conditions as the body interacts with a highly limited work field, selective tasks and overproduction common in the workplace today.

Readings were taken during maximum co-contraction of the fingers and thumb in extension by a high-resolution computer automated data logging force displacement system for the carpus.

Table I: Sample Volar Carpal Transmission Force (VCTF) of EMG Positive Patients
EMG Positive	Body Size/Age/Sex	Symptom Duration	Profession	Kg/force
Mild	Small/50/F	3 months	Hairdresser	03.5
Moderate	Medium/55/F	2 Years	Case manager	08.0
Moderate	Large/50/M	3 Months	Warehouseman	06.8
Severe	Large/50/M	2 Years	Construction	08.6

TED proposes that 1) upper extremity planes of motion and corresponding musculature are favored producing increased muscular capacity and range of motion in internal rotation, adduction and flexion. 2) Over facilitation of one muscle group through activities is known to inhibit the opposing one with resultant shortening/strengthening and lengthening/weakening respectively. 3) Lost opposing muscle forces diminish joint stability, influence alteration of ligament length, modify biomechanics, interfere with proprioception and strongly encourage harmful compensatory behaviors. 4) During a voluntary coordinated effort to negotiate grasp and/or co-contract in activities of the hand, increased and prolonged VCTF causes the carpus to engage in two ways I) longitudinal correction or volar carpal translation and II) transverse correction or overflow residual pulley forces modifying or diminishing transverse carpal dimensions.

Forces acting on the carpus in a volar direction were not previously known. Theoretically the result of TED is diminished carpal volume, tissue changes, mechanical disadvantage and nerve encroachment. Objectively, Volar Carpal Translation (VCT) and Transmission Forces (VCTF) offer a window into little known component function that may enhance our understanding of wrist pathology.

Materials and methods of the automated data logging system will be presented along with average values and images of VCT and VCTF of norms and patients EMG positive.