I. Background
(A) Osteoarthritis
Osteoarthritis (OA), also known as degenerative arthritis, is the most prevalent type of arthritis, and affects an estimated 27 million Americans [1]. As with other forms of arthritis, OA primarily affects a person’s joints and is characterized by the degradation and possible inflammation of the cartilage and synovial fluid respectively around the joint [2]. OA is different from other forms of arthritis in that it is believed to be caused by a combination of damage due to mechanical stress and insufficient joint repair by joints and primarily affects joints that experience a relatively higher amount of force (i.e. hands, feet, spine, hips, knees etc.). In typical cases of OA, the articular cartilage encasing the end of the bones at the joint has been worn away through ‘wear and tear’ or overuse. The articular cartilage at the ends of these bones is a near friction-less surface and due to lack of nerve endings or blood supply, cushions the joint space. The articular cartilage can consequently allow for smooth, pain free interaction and let bones easily slide past one another. When this articular cartilage is worn away due to the previously mentioned overuse, the repair process involves a remodeling of the joint. However this repair process can eventually be insufficient, and can lead to a narrowing of the joint and eventual bone-on-bone contact, resulting in the painful grinding of the bones and inflammation. The bone thickens due to increased loading and remodeling, and painful osteophytes or spurs can result (refer to Figure 1) [3].
OA has been shown to be more prevalent in the elderly and postmenopausal women. Studies have linked this to the decreased bone density of these two populations [4]. Other risk factors for OA include heavy physical loading, repetitive motions, obesity, and genetic bone density deficiencies [5] [6].
(B) Carpometacarpal Arthritis
The carpometacarpal (CMC) joint is “a diarthrodial saddle joint comprised of two major articulations, the trapeziometacarpal articulation to the thumb and the scaphotrapezial articulation, as well as two lesser articulations, the trapeziotrapezoid and the trapeziometacarpal to the index finger, determined by the axis of thumb compression and function.”[7] The physical location of the CMC joint in the hand can be seen in Figure 2. With the frequent use of the hand and thumb in daily human activity, the CMC joint, a saddle shaped joint, can be stressed in three main planes of movement: abduction-adduction, flexion-extension, and opposition [7]. CMC arthritis is a very common and often debilitating form of OA. This form of OA largely affects women in their 50s-70s (post-menopausal) and can result in significant degeneration of the joint including: narrowing of the joint space, bone spur formation, attenuation of surrounding ligaments, and subluxation of the joint (subluxation is described as a partial dislocation) [7] [8] (refer to Figure 3). With continued use of the hand, patients with CMC arthritis experience increasing pain in conjunction with decreased grip and pinch strength.
(i) Prevalence
The prevalence of CMC arthritis of the thumb has been demonstrated to increase with age and largely affects post-menopausal women, with 6 females diagnosed with CMC arthritis for every 1 male [9]. Studies have shown that up to 25% of women and 8% of men will develop radiographic evidence of CMC arthritis in their lifetime. When questioned 28% of women with CMC arthritis and 55% with CMC arthritis and scaphotrapezial (wrist joint) arthritis will complain of pain (See Table 1). Similar data was not available for men. This large patient population justifies continued research into better solutions for CMC arthritis and its symptoms, as well as improved solutions for OA in general.
(ii) Diagnosis
In diagnosing CMC Arthritis, physicians consider a number of factors. The typical presentation for CMC Arthritis is a female from 50-70 years of age, complaining of a radial pain at the base of the thumb that worsens with continued use of the hand. Typical CMC arthritis patients also complain of diminished ability to perform activities of daily living (typing, grasping, childcare etc.), decreased strength, and less dexterity in the digit [7].
During a physical exam of CMC arthritis patients, physicians will often find subluxation of the joint due to weakened joint ligaments and muscle imbalance around the joint. (refer to Figure 4) For more advanced CMC arthritis patients, crepitus (a crackling or popping sound) may be heard when pressure is applied to the joint, indicating bone-on-bone contact [7].
Radiographic evidence can confirm CMC arthritis diagnosis and help classify the stage of the disease (see Figure 5 on following page). Stress view images are taken in standard, lateral, and oblique view to assess the amount of joint space loss and subluxation of the CMC joint [7]. CMC Arthritis can first be classified through the Burton classification system, which divides the disease into 4 stages (See Table 2 below).
(iii) Current Treatment & Pain Management
As discussed later in the Existing Solutions Section of this paper, common treatments used to alleviate pain from CMC arthritis include: activity modification, use of thermal therapy, anti-inflammatory medication, pain medication, splints for joint stabilization, cortisone injection, as well as surgical joint reconstruction for late stage CMC arthritis. Physicians will begin treating CMC arthritis patients with conservative, non-operative therapy before surgical intervention is considered [7]. The first line of treatment is generally reduction of thumb activity, anti-inflammatory drug prescription, and splinting. This approach can be summarized by the Eaton Classification System, which relies only on radiographic evidence and excludes the patient’s complaints and physical examination findings from the stage determination process (See Figure 6 below), and is used in clinical context to determine the best treatment option for an individual patient. The goals of initial conservative treatment are to maximize a patient’s activity of daily living and quality of life, while reducing pain as much as possible. This is an often much more desired line of treatment due to its cost-efficiency (Tiffany Harmon). If conservative treatment fails, and the patient’s CMC arthritis progresses to a more advanced stage, surgical intervention is considered, which is beyond the scope of our project.
II. Need
“I have been working with patients for over ten years that have expressed frustration with the lack of conservative options for the pain that they experience with [CMC arthritis].
I treat patients that are pre and post-surgical, both requiring some form of orthosis to support the first metacarpal and decrease loading across the CMC joint.”
- Tiffany Harmon OT (Hand Specialist)
Tiffany Harmon, an occupational therapist who specializes in hand treatment, claims that there is a lack of innovative pain relief mechanisms that can be integrated with the most common conservative treatment for CMC arthritis: splinting. Splints allow for the immobilization of the CMC joint and can help prevent further degradation and pain. With splints, patients can continue with activities of daily living, including work or physical labor. However in order to apply any pain relief therapy, such as topical creams or thermal therapy, the splint must be removed, disrupting the patient’s livelihood. In addition, often these pain relief therapies are inconsistent or ineffective when applied by the patient themselves, as there is a dearth of effective user-controlled therapeutic systems on the market. Based on information from our client, and our own research into existing options for CMC arthritis pain-alleviation, we believe there is a need for a user-controlled pain alleviation system that can be easily integrated with current CMC arthritis splint design.
III. Project Scope
Carpo-Metacarpal (CMC) arthritis is a degenerative joint disease that results in radial thumb pain. Studies show that 25% of women and 8% of men will develop radiographic evidence of degeneration of the CMC joint. This disease is largely presented in females between 50-70 years of age. It varies in severity (Stage I-IV, Eaton Classification). Treatment varies from conservative, non-invasive methods to surgical, reconstructive methods. Currently, the most utilized conservative treatment is the use of wrist splints. Temperature therapy, cortisone injections, and other treatments have been shown to effectively alleviate pain in many arthritic patients [7]. However, none of these therapies have been integrated into current CMC splints.
The aim of this project is to incorporate a user-controlled therapeutic system into an existing CMC arthritis splint. We will begin by identifying pain-alleviation (therapy) systems. Initially, we will evaluate them based on cost, power efficiency, durability, portability, invasiveness, and compatibility with current splint designs (some criterion will only be relevant for certain types of therapy). In order to properly regulate the therapy, we will integrate a feedback-control system. The final idealized prototype should (1) not interfere with functionality of the splint, (2) be portable, (3) immobilize the wrist, and (4) maintain the “thumb-C-arch” common to splint design.
(A) Osteoarthritis
Osteoarthritis (OA), also known as degenerative arthritis, is the most prevalent type of arthritis, and affects an estimated 27 million Americans [1]. As with other forms of arthritis, OA primarily affects a person’s joints and is characterized by the degradation and possible inflammation of the cartilage and synovial fluid respectively around the joint [2]. OA is different from other forms of arthritis in that it is believed to be caused by a combination of damage due to mechanical stress and insufficient joint repair by joints and primarily affects joints that experience a relatively higher amount of force (i.e. hands, feet, spine, hips, knees etc.). In typical cases of OA, the articular cartilage encasing the end of the bones at the joint has been worn away through ‘wear and tear’ or overuse. The articular cartilage at the ends of these bones is a near friction-less surface and due to lack of nerve endings or blood supply, cushions the joint space. The articular cartilage can consequently allow for smooth, pain free interaction and let bones easily slide past one another. When this articular cartilage is worn away due to the previously mentioned overuse, the repair process involves a remodeling of the joint. However this repair process can eventually be insufficient, and can lead to a narrowing of the joint and eventual bone-on-bone contact, resulting in the painful grinding of the bones and inflammation. The bone thickens due to increased loading and remodeling, and painful osteophytes or spurs can result (refer to Figure 1) [3].
OA has been shown to be more prevalent in the elderly and postmenopausal women. Studies have linked this to the decreased bone density of these two populations [4]. Other risk factors for OA include heavy physical loading, repetitive motions, obesity, and genetic bone density deficiencies [5] [6].
(B) Carpometacarpal Arthritis
The carpometacarpal (CMC) joint is “a diarthrodial saddle joint comprised of two major articulations, the trapeziometacarpal articulation to the thumb and the scaphotrapezial articulation, as well as two lesser articulations, the trapeziotrapezoid and the trapeziometacarpal to the index finger, determined by the axis of thumb compression and function.”[7] The physical location of the CMC joint in the hand can be seen in Figure 2. With the frequent use of the hand and thumb in daily human activity, the CMC joint, a saddle shaped joint, can be stressed in three main planes of movement: abduction-adduction, flexion-extension, and opposition [7]. CMC arthritis is a very common and often debilitating form of OA. This form of OA largely affects women in their 50s-70s (post-menopausal) and can result in significant degeneration of the joint including: narrowing of the joint space, bone spur formation, attenuation of surrounding ligaments, and subluxation of the joint (subluxation is described as a partial dislocation) [7] [8] (refer to Figure 3). With continued use of the hand, patients with CMC arthritis experience increasing pain in conjunction with decreased grip and pinch strength.
(i) Prevalence
The prevalence of CMC arthritis of the thumb has been demonstrated to increase with age and largely affects post-menopausal women, with 6 females diagnosed with CMC arthritis for every 1 male [9]. Studies have shown that up to 25% of women and 8% of men will develop radiographic evidence of CMC arthritis in their lifetime. When questioned 28% of women with CMC arthritis and 55% with CMC arthritis and scaphotrapezial (wrist joint) arthritis will complain of pain (See Table 1). Similar data was not available for men. This large patient population justifies continued research into better solutions for CMC arthritis and its symptoms, as well as improved solutions for OA in general.
(ii) Diagnosis
In diagnosing CMC Arthritis, physicians consider a number of factors. The typical presentation for CMC Arthritis is a female from 50-70 years of age, complaining of a radial pain at the base of the thumb that worsens with continued use of the hand. Typical CMC arthritis patients also complain of diminished ability to perform activities of daily living (typing, grasping, childcare etc.), decreased strength, and less dexterity in the digit [7].
During a physical exam of CMC arthritis patients, physicians will often find subluxation of the joint due to weakened joint ligaments and muscle imbalance around the joint. (refer to Figure 4) For more advanced CMC arthritis patients, crepitus (a crackling or popping sound) may be heard when pressure is applied to the joint, indicating bone-on-bone contact [7].
Radiographic evidence can confirm CMC arthritis diagnosis and help classify the stage of the disease (see Figure 5 on following page). Stress view images are taken in standard, lateral, and oblique view to assess the amount of joint space loss and subluxation of the CMC joint [7]. CMC Arthritis can first be classified through the Burton classification system, which divides the disease into 4 stages (See Table 2 below).
(iii) Current Treatment & Pain Management
As discussed later in the Existing Solutions Section of this paper, common treatments used to alleviate pain from CMC arthritis include: activity modification, use of thermal therapy, anti-inflammatory medication, pain medication, splints for joint stabilization, cortisone injection, as well as surgical joint reconstruction for late stage CMC arthritis. Physicians will begin treating CMC arthritis patients with conservative, non-operative therapy before surgical intervention is considered [7]. The first line of treatment is generally reduction of thumb activity, anti-inflammatory drug prescription, and splinting. This approach can be summarized by the Eaton Classification System, which relies only on radiographic evidence and excludes the patient’s complaints and physical examination findings from the stage determination process (See Figure 6 below), and is used in clinical context to determine the best treatment option for an individual patient. The goals of initial conservative treatment are to maximize a patient’s activity of daily living and quality of life, while reducing pain as much as possible. This is an often much more desired line of treatment due to its cost-efficiency (Tiffany Harmon). If conservative treatment fails, and the patient’s CMC arthritis progresses to a more advanced stage, surgical intervention is considered, which is beyond the scope of our project.
II. Need
“I have been working with patients for over ten years that have expressed frustration with the lack of conservative options for the pain that they experience with [CMC arthritis].
I treat patients that are pre and post-surgical, both requiring some form of orthosis to support the first metacarpal and decrease loading across the CMC joint.”
- Tiffany Harmon OT (Hand Specialist)
Tiffany Harmon, an occupational therapist who specializes in hand treatment, claims that there is a lack of innovative pain relief mechanisms that can be integrated with the most common conservative treatment for CMC arthritis: splinting. Splints allow for the immobilization of the CMC joint and can help prevent further degradation and pain. With splints, patients can continue with activities of daily living, including work or physical labor. However in order to apply any pain relief therapy, such as topical creams or thermal therapy, the splint must be removed, disrupting the patient’s livelihood. In addition, often these pain relief therapies are inconsistent or ineffective when applied by the patient themselves, as there is a dearth of effective user-controlled therapeutic systems on the market. Based on information from our client, and our own research into existing options for CMC arthritis pain-alleviation, we believe there is a need for a user-controlled pain alleviation system that can be easily integrated with current CMC arthritis splint design.
III. Project Scope
Carpo-Metacarpal (CMC) arthritis is a degenerative joint disease that results in radial thumb pain. Studies show that 25% of women and 8% of men will develop radiographic evidence of degeneration of the CMC joint. This disease is largely presented in females between 50-70 years of age. It varies in severity (Stage I-IV, Eaton Classification). Treatment varies from conservative, non-invasive methods to surgical, reconstructive methods. Currently, the most utilized conservative treatment is the use of wrist splints. Temperature therapy, cortisone injections, and other treatments have been shown to effectively alleviate pain in many arthritic patients [7]. However, none of these therapies have been integrated into current CMC splints.
The aim of this project is to incorporate a user-controlled therapeutic system into an existing CMC arthritis splint. We will begin by identifying pain-alleviation (therapy) systems. Initially, we will evaluate them based on cost, power efficiency, durability, portability, invasiveness, and compatibility with current splint designs (some criterion will only be relevant for certain types of therapy). In order to properly regulate the therapy, we will integrate a feedback-control system. The final idealized prototype should (1) not interfere with functionality of the splint, (2) be portable, (3) immobilize the wrist, and (4) maintain the “thumb-C-arch” common to splint design.