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Research Review By Dr. Laurie Hung©

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Date Posted:

July 2012

Study Title:

Radial Nerve Mobilization Decreases Pain Sensitivity and Improves Motor Performance in Patients with Thumb Carpometacarpal Osteoarthritis: A Randomized Controlled Trial

Authors:

Villafane JH, Guillermo BS, Mark DB, et al.

Author's Affiliations:

Residenze Sanitarie Assistenziali - Department of Physical Therapy, Italy; Rey Juan Carlos University – Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Spain; Mons. Carols V. Cruvelier Foundation and J. Robert Cade Foundation – Department of Physiology, Spain; Catholic University of Cuyo – Department of Physiology, School of Nutrition, Biochemistry and Pharmacy, Argentina; University of Florida – Department of Physical Therapy and Center for Pain Research and Behavioural Health, Florida; European University of Madrid – Research Group of Musculoskeletal Pain and Motor Control, Spain

Publication Information:

Archives of Physical Medicine and Rehabilitation 2012; 93; 396-403.

Background Information:

The first carpal-metacarpal (CMC) joint is the second most common site of osteoarthritis (OA), with 30-50% of post-menopausal women and 40-50 year old men suffering from thumb CMC OA (1,4). This condition is mainly caused by degeneration (deterioration of superficial surfaces of joint and ectopic bone regeneration) of the trapeziometacarpal joint. OA of the CMC joint has also been shown to be strongly associated with OA of the scaphotrapeziotrapezoid joint (1). Symptoms include pain at the base of the thumb and decreased function of the joint (4). It has been suggested that the pain associated with this condition could also be facilitated by a central sensitization mechanism. The trapeziometacarpal joint permits tweezer-like movements for precision grip, and is involved in the gripping capabilities of the hand. Patients may report disability during specific activities including writing, gardening, turning taps, and opening jars, with pain frequently localized at the palmar surface of the joint (3).

Thumb CMC OA accounts for the largest number of OA related surgical procedures in the United States. Surgical management of thumb CMC OA is usually only partially successful (1, 2). Conservative treatment for thumb OA include exercises, non-steroidal anti-inflammatory drugs, splints, and steroid injections, however few studies have evaluated their effectiveness (1, 3). No evidence-based consensus or guideline exists for the treatment of thumb CMC OA (4).

Neurodynamic techniques are a form of manual therapy directed to the neural structures through positioning and movement of multiple joints. To date there is limited evidence to support their use in managing musculoskeletal pain disorders, however researchers have found small advantages (changes in pain sensitivity) in patients treated with this method (3). There are 2 general methods used to apply neurodynamic techniques: sliding and tensioning. Sliding techniques consist of alternating combinations of movements of at least 2 joints in which one movement loads the peripheral nerve (increasing tension in the nerve), while the other movement simultaneously unloads the nerve (decreasing tension in the nerve). Tensioning techniques produce more strain in the nerve than sliding.

The aim of this study was to confirm that neurophysiologic changes occur (hypoalgesia, increased strength)I n the upper limb in response to a neurodynamic sliding technique of the radial nerve (radial nerve flossing), and to extend these findings to a different peripheral musculoskeletal pain condition.

Pertinent Results:

  • 2 men and 28 women formed the radial mobilization group, mean age 80.87 years.
  • 4 men and 26 women formed the placebo group, mean age 81.73 years.
  • All subjects were right-hand dominant, and no significant differences were noted between groups
Mechanical Pain Sensitivity:
  • On the whole, results show that the intervention had an immediate effect on mechanical pain sensitivity.
  • Trapeziometacarpal joint:: Treatment increased PPT by 3.33 +/- .24 kg/cm2 (p < .001) in the trapeziometacarpal joint and this was maintained until first and second follow-up.
  • Scaphoid bone: All participants in both groups demonstrated an increase in PPT over the first month and this was maintained to a higher degree in the treatment group at 2 months.
  • Hamate bone: PPT increased until the 1st follow-up in the treatment group, at which point it became roughly equivalent to the control group’s values.
Motor Performance:
  • Radial nerve mobilization increased strength compared with the placebo in the tip pinch (12.2% treatment vs. -3% control, and 7.2% vs. -7% at the first follow-up) and the tripod pinch (13.1% treatment vs. 0.4% control, and 8.1% vs. 2.5% at the first follow-up), demonstrating a substantially increased motor control in tip pinch and tripod pinch in patients in whom radial mobilization was applied

Clinical Application & Conclusions:

Radial nerve mobilization produced significant mechanical hypoalgesia and increased pinch strength in patients with dominant hand thumb CMC OA. The sliding technique, or nerve flossing, is suggested to be used for a chronic pain condition such as OA pain, in which central or peripheral sensitization has been found, because the technique is less aggressive than more direct interventions such as surgery or steroid injection.

Overall, this study suggests that radial nerve mobilization (or nerve flossing) may be useful in the management of thumb CMC OA in addition to joint mobilizations, exercises, and/or modalities.

Study Methods:

Protocol:
  • This study was a double blind, randomized controlled trial
  • All subjects had previously been diagnosed with stage III or IV secondary thumb CMC OA in the dominant hand (confirmed radiographically).
  • Each subject attended 6 intervention sessions on separate days at the same time of day.
  • Three baseline pressure pain threshold and pinch strength measurements were collected once at the beginning of the study
  • After baseline measurements were taken, subjects were randomly assigned to either the control or test group using GraphPad software.
  • Subjects received 6 treatments on separate days from a physiotherapist with 7 years of clinical experience.
  • Post-treatment pressure pain threshold, pinch strength, and grip strength measurements were collected 5 minutes after the treatment each time.
  • Follow-up measurements were collected at 1 and 2 months post-treatment.
Outcome Measures:
  • Mechanical pain sensitivity was quantified by measuring pressure pain thresholds (PPT).
  • PPT measurements were performed using a mechanical pressure algometer with a 1 cm2 rubber-tipped plunger mounted on a force transducer. Pressure was applied at a rate of 30 kPa/s.
  • Three points were used: the trapeziometacarpal joint at the bottom of the anatomic snuffbox, tubercle of the scaphoid bone, and unciform apophysis of the hamate bone.
  • The average of 3 measurements was calculated and used for the main analysis. These measurements were collected with a 1 minute pause between them.
Motor strength was quantified by measuring pinch strength:
  • Pinch strength was evaluated with a mechanical pinch gauge in a seated position with the shoulder adducted and neutrally rotated and the elbow flexed at 900.
  • Two different measurements were taken: tip pinch between index and thumb fingers, tripod pinch between index and middle fingers and the thumb.
Interventions:
  • The radial nerve mobilization consisted of a sliding mobilization of the proximal-distal radial nerve.
  • The patient was supine and the physiotherapist seated. The physiotherapist depressed the patient’s shoulder girdle, extended the patients elbow, and then internally rotated the arm. The patient’s wrist, thumb, and all the fingers were fully flexed, and the hand was placed into ulnar deviation.
  • Once in this position, 2 movements were performed: 1) shoulder depression was applied simultaneously with elbow flexion and wrist extension and 2) shoulder elevation was performed with elbow extension, wrist flexion, and ulnar deviation.
  • These motions were alternated at a rate of approximately 2 seconds per cycle (1s into extension and 1s into flexion).
Placebo treatment was inactive and nontherapeutic doses of pulsed ultrasound with an intensity of 0 W/cm2 and gentle application of an inert gel to the hypothenar area of the dominant hand.

Data was analyzed using SPSS for Windows. Normal distribution was assessed with the Kolmogorov-Smirnov test. All measures fitting a normal distribution were tested using a 2-way ANOVA.

Study Strengths / Weaknesses:

Strengths:
  • Both the subjects and investigators were blinded, and the treating clinician was blinded to subjects’ baseline measurements
  • An experienced clinician delivered the treatment protocols to subjects.
Weaknesses:
  • The sham used in this study was very different from the test procedure (ultrasound vs. nerve flossing). A sham manual procedure of the upper limb may have been a more effective control.
  • 90% of the subjects were women. This may limit the generalizability of the study findings.
  • No pain or disability scales were used to monitor the subjects’ progress. These could have confirmed the PPT and pinch strength findings.
  • The authors note that grip strength was collected at post-treatment, but do not report this data in the results.

Additional References:

  1. Kapoutsis DV, Dardas A, Day CS. Carpometacarpal and Scaphotrapeziotrapezoid Arthritis: Arthrscopy, Arthroplasty, and Arthrodesis. J Hand Surg 2011; 36A: 354-366.
  2. Moriatis J, Delaronde S. Current Trends in Nonoperative and Operative Treatment of ; Trapeziometacarpal Osteoarthritis: A Survey of US Hand Surgeons. J Hand Surg 2012; 37A: 77-82.
  3. Villafane JH, Guillermo BS, Fernandez-Camero J. Effect of Thumb Joint Mobilization on Pressure Pain Threshold in Elderly Patients with Thumb Carpometacarpal Osteoarthritis. J Manipulative Physiol Ther 2012; 35: 110-120.
  4. Spaans AJ, van Laarhoven CMCM, Schuurman AH, et al. Interobserver Agreement of the Eaton-Littler Classification System and Treatment Strategy of Thumb Carpometacarpal Joint Osteoarthritis. J Hand Surg 2011; 36A: 1467-1470.

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