Osteoarthritis of the hand is a chronic joint disease that usually affects one or more of the finger joints and it is a major cause of disability. Radiology and the Eaton-Littler classification (Stages I-II-III-IV) are used for its diagnosis. The treatment of stages I, II and in some cases of stage III, is based on pharmacological and rehabilitation measures, including the use of orthoses or splints.

The development of Biosplint 3D will allow a qualitative leap forward in the search for an intelligent solution for patients with rhizarthrosis (Degenerative alteration of the trapezius-metacarpal joint (TMJ) characterized by a progressive deterioration of the articular surfaces and new bone formation in them).

The aim of the study is to assess the feasibility of applying a personalized splint versus a conventional one. It is not a design aimed at evaluating the efficacy of such treatment. It is a prospective study with two arms, open with 1:1 allocation.

The study includes a recruitment visit and two follow-up visits, one at a month and a final visit at 3 months. Patients with a new diagnosis of osteoarthritis of the trapeziometacarpal joint are included. One group of patients wears the usual splint indicated by the personalized doctors of the Service and the other group wears the 3D bi-splint.

The main variable is pain, which will be measured by a visual analog scale (VAS). In addition, the DASH questionnaire (Disabilities of the Arm, Shoulder and Hand) and questions about patient satisfaction with the use of splints will be used.

Osteoarthritis of the TMJ is a disease present in a large part of the general population. The symptomatic prevalence is estimated at 6-8% of the population, although its radiological prevalence would be 29-76%. Its diagnosis is basically clinical, although radiological tests are very useful to confirm it and to typify the evolution of the disease.

The TMJ has a great range of mobility, since it basically serves to oppose the thumb to the rest of the fingers and to carry out grasping or pinching actions, which is why it is of great use and of great utility in everyday life. This range of movements is favored by being a not very congruent joint, but this fact also explains the tendency to instability, which can lead to abnormal movements between the joint surfaces, which ultimately lead to the development of osteoarthritis of the joint. joint. Over time, a subluxation occurs and the first metacarpal tends to approach the rest of the fingers, producing an adduction. This osteoarthritis leads to pain and functional disability. The pain is usually greater when the joint is stressed, during pincer movements.

• Conventional orthoses

Currently there are several types of splints on the market made of temperature-moldable plastic material, a splint that has multiple disadvantages in terms of manufacture:

• Polypropylene shrinks with heat, so it must be taken into account when designing. In addition, special care must be taken when heating and thermoforming it since the orthosis can collapse more easily. If it is not heated, it may not thermoform well.
• You cannot make rectifications, so you have to be careful with the mold and make screeds or modifications before adapting the polypropylene, since once it has been fused no changes can be made.

Another type of splints that exist on the market are splints made of polyethylene sheets adjustable with velcro. The disadvantage of these splints is their instability in immobilization: they do not hold firmly, since they do not fit perfectly to the affected area.

• Advantages of the 3D bioferula

The splints developed using this method have a series of advantages both in manufacturing and for patients, among which we can highlight:

• Increase the precision in the design of the splint to place it in the affected area.
• Reduce the weight of the splint in order to lead a more agile life.
• Improve perspiration.
• Water resistance, which will improve hygiene, the patient can even bathe with the splint on.
• Greater mobility. The "pincer" movement will not be affected.
• Allow air circulation.
• Improve aesthetic appearance: simple splint design that can be covered if the patient considers it so, for example, with gloves.
• Manufacturing times: the 3D model is made in 3 hours and can be in use by the patient in 72 hours.
• It can be made with fully recyclable materials.

Inclusion Criteria:

• Clinical diagnosis of osteoarthritis of the trapeziometacarpal joint.
• Radiological stage of Eaton-Littler classification I / II.
• Patients in whom the placement of a discharge splint is clinically indicated.
• Score between 3 and 7 on the VAS pain scale (range 0 to 10).

Exclusion Criteria:

• Previous treatment of osteoarthritis of the trapeziometacarpal joint.
• Refuses to participate in the study.
• Disabilities that prevent the completion of the questionnaires.
• Presence of severe deformations in the hand.
• Presence of other alterations, such as carpal tunnel syndrome, tendonitis or chronic inflammatory arthropathies.

Patients with a new diagnosis of osteoarthritis of the trapeziometacarpal joint