Management of the Osteoarthritic Thumb Carpometacarpal Joint






CRITICAL POINTS





  • Degree of thumb pain often does not correlate with radiographic findings, which also may not correlate with true degree of arthrosis as seen arthroscopically.



  • Most patients improve with conservative means, including orthotic positioning, activity modification, and occasional corticosteroid injection.



  • Surgical options vary greatly, and most patients with advanced disease do well regardless of surgery selected.



  • Initial choice of surgical intervention should “burn no bridges,” and newer procedures such as arthroscopy and implant arthroplasty may be less painful with more rapid recovery of function.



The basal joint of the thumb is the second most common location for osteoarthritis in the hand. However, it is generally the most painful site and by far the most functionally disabling, and therefore a major reason why patients seek consultation with a hand surgeon and referral to a hand therapist. While distal interphalangeal joint arthritis is much more common, it is often minimally symptomatic, and outside of corticosteroid injection, fusion remains the only good treatment option at this small joint. This method of treatment is simple, and the results are reproducible with excellent return of function. Conversely, due to the complex kinematics and multiple degrees of freedom seen during basal joint motion, the treatment of basal joint arthritis is much more complex and the results less predictable. Not only is motion at this joint so functionally critical, but incredible stresses are transmitted across the basal joint even with simple, everyday activities. The forces seen at the tip during pinch are transmitted 10- to 13-fold to the base of the thumb. It has been theorized that the basal joint of the thumb is what most separates humans from other primates, and its role in tool making separates us from the remainder of the animal kingdom.




Assessment


The diagnosis of basal joint arthritis is usually made by simple clinical means. Generally, patients will point to the affected area and will complain of pain, often coupled with pinch weakness or crepitus at the trapeziometacarpal joint. Occasionally, the pain will be more generalized or quite vague in nature, and a more directed physical examination will elucidate the location of the painful arthritis. A positive “shoulder sign” may be seen, which is a visible stepoff seen at the base of the metacarpal, due to either trapeziometacarpal subluxation or prominent osteophytes arising from either bone. In earlier stages the gross appearance may be normal, but the pain often begins on the palmar aspect of the joint; hence the tenderness may be found over the most medial aspect of the thenar eminence. Progression of disease often leads to subluxation, and one can palpate this instability by gentle traction on the thumb, coupled with downward pressure exerted on the metacarpal base. This may lead to pain along with crepitus. The pain can be more directly obtained by axial compression on the metacarpal followed by rotational movement—the so-called grind test. As arthritis progresses the trapeziometacarpal motion often diminishes, and patients may develop an adduction contracture. Radial abduction of the thumb greatly diminishes, and a compensatory hyperextension may occur at the thumb metacarpophalangeal (MCP) joint so as to allow any functional abduction. This resultant Z -deformity may be quite disfiguring and is the hallmark of very advanced thumb carpometacarpal (CMC) arthritis ( Fig. 105-1 ). Surprisingly, many patients are remarkably asymptomatic at this advanced stage, and one must assess the patient’s functional needs as well as determine need for pain relief.




Figure 105-1


Advanced osteoarthritis noted with shoulder sign at prominent basal joint with compensatory metacarpophalangeal joint hyperextension leading to Z -deformity.


Basal joint arthritis is often associated with a variety of concomitant painful hand maladies, and the clinician should rule out associated carpal tunnel syndrome. The presence of flexor stenosing tenosynovitis of the thumb and other digits (trigger finger) should be assessed as well as the ubiquitous DeQuervain’s stenosing tenosynovitis of the first extensor compartment. The latter can often be confused with basal joint arthritis, and careful physical examination is often necessary to distinguish the two, at the same time understanding that they often present together as well.


Invariably, radiographs of the hand will not only confirm but also determine the extent of osteoarthritic changes present at the trapeziometacarpal joint. A well-accepted radiographic staging system, described by Eaton and Glickel, serves as a standard to compare patients for clinical studies, and gives the clinician a yardstick to determine progression of disease. Eaton stage I arthritis demonstrates minimal radiographic changes, with trapeziometacarpal widening that may represent joint swelling. Stage II begins to show joint narrowing along with early marginal osteophytes and perhaps some subluxation. Stage III is characterized by larger osteophytes and often marked joint space narrowing along with subchondral sclerosis and even cyst formation. Lax joints will show even further subluxation, and the presence of metacarpal adduction should be assessed. Stage IV represents pantrapezial arthrosis, where both the trapeziometacarpal and scaphotrapezial joints are involved.


Routine posteroanterior and lateral view radiographs should be obtained, and one can consider a stress view where the thumb tips are pressed against each other allowing for better determination of the degree of trapeziometacarpal subluxation. A Robert’s pantrapezial view, which gives superior assessment of the trapezium as a whole “en face,” allows evaluation of the scaphotrapezial and trapezoidal joints, the first and second metacarpal base interval, as well as the trapeziometacarpal joint. While this view requires considerable arm internal rotation on the part of the patient, it does give a superior view of the pantrapezial joints and allows detection of even small medial-sided osteophytes as well as accurate assessment of joint subluxation. Live fluoroscopy can add further information by assessing active and passive joint motion and to look at multiple views.


Associated radiographic findings should be inspected, such as MCP joint hyperextension, so often coupled with the thumb metacarpal adduction posture already mentioned. The trapezium morphology itself should be carefully assessed, since a sloping trapezium has been correlated with a higher incidence of basal joint osteoarthritis. Surrounding joints should also be inspected for arthritic changes, such as the MCP joint, and more commonly the thumb and digit distal interphalangeal joints.


Routine basal joint arthritis rarely requires other imaging modalities to secure the diagnosis. MRI may demonstrate cartilage loss in early stages if the correct technique and protocol are used, and a bone scan will show increased uptake that is quite sensitive but minimally specific as to the etiology.


A combination of careful physical examination and routine radiographs will suffice in allowing the clinician to diagnose basal joint osteoarthritis, as well as determine where that patient fits in along the severity spectrum. This initial assessment will often determine the treatment plan, now increasingly varied, that can be offered to the patient suffering from this common malady.




Conservative Management


The treatment of symptomatic basal joint arthritis is most often initially palliative. Anti-inflammatory drugs, orthotic positioning, and even corticosteroid injections simply give pain relief. They generally do not alter the often inevitable course of progressive pain and even deformity. Days and colleagues conducted one of the few prospective studies looking at the short- and long-term effects of a single corticosteroid injection into the basal joint followed by a 3-week course of orthotic positioning. They found that Eaton stage I patients did well on a short-term basis with modest decline in the outcome over time, while stage IV patients had no measurable relief at either interval. Less than 50% of stage II and III patients had any sustained improvement in the long term. Interestingly, the patients who did well generally had about 95% of grip strength as compared with the unaffected side, while the poor responders had less than two thirds of contralateral grip strength.


Swigart and colleagues were among the first authors to simply look at efficacy of orthotic positioning alone as a conservative treatment for symptomatic basal joint arthritis. They retrospectively assessed 114 patients for improvement of symptoms using a thumb spica orthosis and found that three quarters of early-stage patients had improvement, and even one half of patients at the advanced stages demonstrated benefit. They found it was a well-tolerated and efficacious method of treatment but that it did not completely eliminate the symptoms. This sentiment was shared by many clinicians in several roundtable discussions published discussing the efficacy of orthotic positioning, as well as surgical intervention, in managing the painful basal joint. Clinical studies have looked extensively at the benefits of different orthotic positioning options, suggesting that neoprene flexible orthoses are best tolerated.


Corticosteroid injections are generally a key component of the treating surgeon’s armamentarium for treatment of basal joint arthrosis. However, even this treatment has not been free of scrutiny. A recent prospective, randomized, and double-blinded trial comparing corticosteroid injection versus hylan G-F 20 and placebo revealed that there were no differences in most of the outcome measures at any of the time points. However at 4 weeks postinjection, the steroid group did demonstrate the best improvement in symptoms. Hylan G-F 20 seemed to have greater efficacy at a later time period. This was confirmed in a study directly comparing both types of injections, indicating that pinch and grip strength were best improved in the late follow-up by the use of hylan G-F 20.


In any case, most clinicians will use corticosteroid injections, often in concert with orthotic repositioning, as personal observation has supported at least a temporary improvement in the painful symptoms. To improve joint penetration and, hence, efficacy, injection can be combined with fluoroscopic control ( Fig. 105-2 ). The role of hylan G-F 20 has yet to be fully elucidated, but it seems that early studies are supporting its use, particularly for a longer term treatment, as seen in other joints such as the knee.




Figure 105-2


Fluoroscopic view demonstrating successful intra-articular injection of corticosteroid. This is helpful, as prominent osteophytes may make joint localization difficult otherwise.


Conservative treatment is often not effective, because nothing is being done to change the joint itself. Since pinching activity is so ubiquitous in everyday life as well as work, the joint continues to experience stresses that propagate the symptomatic arthritis. Persistent pain demands that something more definitive be instituted for treatment. For this reason, surgery has generally been the mainstay of treatment in symptomatic basal joint arthritis.




Surgical Options


One of the earliest surgical treatments described was complete excision of the trapezium. This was a simple operation first described by Gervis in 1947. It is ironic that we have come full circle regarding surgical treatment, since Meals recently described a similar procedure in the literature nearly 50 years later. A more complex modification of this procedure has been termed the LRTI (ligament reconstruction tendon interposition) and encompasses many different methods, depending on what tendon is used for stabilization and the routing path. In general, this has been and remains the most commonly used surgical procedure for treatment of painful basal joint osteoarthritis. This relatively complex operation combines several previously described procedures encompassing the complete excision of the trapezium bone and stabilization of the metacarpal base using a strip of the flexor carpi radialis (FCR) wrist tendon to stabilize the newly formed joint. While reports in the literature are generally favorable in terms of the outcome, there are several problems that remain with this operation. One of them is that the recovery process is relatively long and can be painful. However, the main problem lies in the fact that there are few salvage options if painful symptoms persist. The reason lies in the simple fact that the trapezium has been completely excised. Once this bone, the pillar base of the thumb, is removed, there are few remedies available to reconstruct the thumb. Similar problems are faced after fusion, since the adjacent joints, which are frequently arthritic as well, can become more symptomatic. Reversing a fusion is a formidable task, and joint replacement may be the only option. It is worthwhile to understand the myriad of options available to the treating surgeon, so that the patient, in concert with the clinician, can make an educated decision as to which option best suits their lifestyle and functional demands placed upon the thumb.




Arthroscopy


It makes sense to first consider arthroscopy as a surgical option when discussing treatment of any joint. This is because it is minimally invasive, gives a great deal of information about the degree of arthritis, and generally allows for rapid recovery. However, it is ironic that this technology has only recently been applied to the basal joint of the thumb, and is still not a universally accepted form of treatment. A recent review of the scant literature on the topic demonstrates this, and suggests a treatment algorithm that encompasses arthroscopy as an option.


The concept of arthroscopy may be most beneficial in the early stages of basal joint arthritis ( Fig. 105-3 ). The earliest presentation of this painful condition has few surgical options once conservative treatment has been exhausted. It is obvious that a 35-year-old active woman may not agree to a complete open excision of the trapezium even when her symptoms are persistent. The other surgical options discussed are also relatively aggressive for the younger, active patient. Hence, failed conservative treatment of basal joint osteoarthritis in the younger, active patient remains a dilemma. However, arthroscopy presents a viable alternative that better determines the true stage of arthrosis, regardless of the radiographic stage. The patient who continues to have pain despite several cortisone injections and prolonged orthotic positioning may very well agree to an arthroscopic procedure. This is because a minimally invasive procedure at this small joint presents the same advantages that it does in larger, but more accepted, procedures such as knee arthroscopy.




Figure 105-3


External view showing setup for basal joint arthroscopy and hand positioning of arthroscope and small joint shaver instrumentation.


An arthroscopic evaluation of this joint gives us the true stage of arthritis and downplays the importance of radiographic staging when it comes to less severe stages of arthritis where minimal radiographic findings may be seen. In fact, an arthroscopic classification has been suggested and can fine-tune the treatment options ( Table 105-1 ). For example, an arthroscopic stage I indicates a joint with significant synovitis but no articular cartilage loss. This patient may gain considerable symptomatic relief by a simple synovectomy and perhaps radiofrequency shrinkage capsulorrhaphy ( Fig. 105-4 ). Rekant and Osterman emphasized the role of type I collagen in lending stability to the trapeziometacarpal joint capsule and its subsequent response to radiofrequency treatment by contracture of the collagen fibrils. However, there have been no long-term studies assessing results of isolated use of radiofrequency in early basal joint arthritis.



Table 105-1

Proposed Badia Arthroscopic Classification of Thumb Trapeziometacarpal Osteoarthritis
















Stage Arthroscopic Changes
I Intact articular cartilage; disruption of the dorsoradial ligament and diffuse synovial hypertrophy; inconsistent attenuation of the anterior oblique ligament (AOL)
II Frank eburnation of the articular cartilage on the ulnar third of the base of first metacarpal and central third of the distal surface of the trapezium; disruption of the dorsoradial ligament + more intense synovial hypertrophy; constant attenuation of the AOL
III Widespread, full-thickness cartilage loss with or without a peripheral rim on both articular surfaces; less severe synovitis; frayed volar ligaments with laxity



Figure 105-4


Arthroscopic view of thermal shrinkage capsulorraphy. Note prominent volar oblique ligament.


The role of radiofrequency capsulorrhaphy in small joints is only recently being explored but may present the same advantages that it has in larger joints. However, it can also lead to the same pitfalls as have been seen treating shoulder instability. Judicious use of this new technology is important, and further studies are necessary regarding its role in the treatment of small-joint arthritis. Current methodology includes the use of focal bipolar radiofrequency thermal capsulorraphy with a variable period of thumb spica immobilization depending upon the degree of capsular laxity.


More advanced arthroscopic stages dictate more aggressive treatment. Stage II arthrosis, which indicates a focal articular cartilage loss, is a good indication to perform an adjunctive osteotomy that alters the joint biomechanics. This osteotomy is a previously described procedure at the thumb metacarpal that has only been recently revisited. The concept is similar to its use for other joints, where the osteotomy alters the force vector passing across the joint, effectively “unloading” the joint. In the case of the thumb trapeziometacarpal joint, a dorsoradial closing-wedge osteotomy ( Fig. 105-5 ) serves to shift the metacarpal more centrally onto the trapezium, counteracting the typical dorsal subluxation commonly seen ( Fig. 105-6 ). It also alters the direct articular contact points seen within the joint, which may halt the progression of a focal defect of chondral loss. The technique of combining arthroscopic debridement, thermal capsulorraphy, and the Wilson-type osteotomy was delineated in a recent technique article that reported on 43 patients with arthroscopic stage II arthrosis undergoing the procedure. While preliminary results are very favorable and no patients have required further surgery, it will be important to follow these patients long term to assess for any radiographic changes and clinical outcome.




Figure 105-5


Small dorsoradial wedge of metacarpal excised during creation of osteotomy via extension of ulnar portal.



Figure 105-6


Intraoperative fluoroscopic view showing .045 K-wire placement for stabilization of metacarpal base osteotomy. Note extension posture of metacarpal and the centralization of metacarpal base on trapezium also maintained with same wire fixation.


Arthroscopic stage III implies nearly complete cartilage loss ( Fig. 105-7 ), and this would be an indication to perform either one of the open procedures, as previously described, or perhaps an arthroscopic interposition arthroplasty. Despite previous discussion where arthroscopy is considered optimal for the earliest stages of arthrosis, the first article published on basal joint arthroscopy was by Menon and described a technique utilizing arthroscopic interposition arthroplasty for more advanced arthritis along with his clinical series. He reported nearly 90% good results in a technique wherein arthroscopic partial trapeziectomy was performed coupled with interposition using either autogenous tendon graft, Gore-Tex (W.L. Gore, Elkton, Maryland), or fascia lata allograft. No additional stabilization was performed, since the capsule is left intact due to the nature of the approach. Even individuals with gross laxity can benefit from this procedure, as evidenced by the results obtained in an Ehlers-Danlos patient who requested that the contralateral thumb be approached using the same arthroscopic interposition arthroplasty.


Apr 21, 2019 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Management of the Osteoarthritic Thumb Carpometacarpal Joint
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