Difference in Patient Reported Outcomes at 1 year after 6 or 8 weeks of carpometacarpal joint distraction: a Randomized Controlled Non-Inferiority Trial.

Carpometacarpal osteoarthritis of the first joint (CMC1 OA) is a very common
degenerative joint disorder resulting in pain, loss of function and cartilage
damage. (1,2) One out of three people aged 55 years or older have symptoms of
CMC1 OA on radiographs and this increases with aging (1). The prevalence of
radiographic CMC1 OA is around 90% for adults aged 80 years and older and 100%
aged 90 and older (2,3). CMC1 OA is initially treated conservatively with
splints and analgesics, both aimed to reduce pain. (4) Hand therapy aims to
increase muscle strength and to educate patients on optimal use of their hands.
These treatment modalities do not stop progression of disease. If conservative
treatment fails, invasive surgical intervention is indicated to provide relief
of symptoms and restore hand functionality. (4-6) There are numerous variations
in surgical treatment for CMC1 OA. The variations involve the amount of
trapezium resected; stabilization of the base of the metacarpal; and the use of
interposition materials or prostheses. (5-7) Osteotomy and arthrodesis are also
considered. (8) There is no evidence that one technique achieves superior pain
relief and decreased limitations. (5-7)

Joint distraction for CMC1 OA is a technical feasible and innovative
therapy for relatively young patients with severe symptoms. (9) In a recent
prospective trial (pilot study) five patients were treated and show favourable
results - reduction of pain and improvement of function - during 12 months of
follow-up. These results even slightly improve at the 24 months follow-up
compared to 12 months (unpulished data). Spaans et al. (9) concludes that joint
distraction can provide clinical benefits in patients with CMC1 joint OA. It
could result in postponing invasive surgical interventions for CMC1 OA but
further studies with a higher number of included patients and long-term effect
are necessary to prove this. Nowadays 40 patients are treated with CMC1 joint
distraction. On average, patients report significantly less pain and better
physical function compared to pre-operative scores (unpublished data).

Among patients suffering from ankle and knee osteoarthritis, joint
distraction is an accepted treatment with excellent results and clinical
improvement. (10-14) Moreover actual repair of joint cartilage has been
demonstrated in distracted joints. Van der Woude et al. (14) shows that five
years posttreatment, patients still report clinical improvement on the WOMAC
questionnaire (an arthritis index) (p = 0.002) and on a pain intensity scale (p
< 0.001) compared to baseline scores. In this study, all patients (n = 20) had
the external distractor device in place for a duration of 8 weeks. A more
recent study performed by the same research team shows that six weeks of
distraction therapy has similar 1-year results compared to eight weeks of joint
distraction. (15) ) In comparison, 11 out of 20 (55%) patients in the six-week
group had significantly less pin tract infections during the distraction
period, than the 85% (17 of 20 patients) in the eight-week groups (p = 0.038).
Pin tract infections were treated with oral antibiotics, one patient was
treated with intravenous antibiotics due to sepsis. In this study both groups
were small (n = 20), no long-time follow-up results are available yet, and no a
priori sample size was calculated. Another study among 57 patients undergoing
knee distraction did not show statistically significant benefit of eight weeks
distraction compared to six weeks either. (16) However, there was a small
benefit on average in the eight weeks distraction group due to greater joint
space width, but this did not reach a statistically significant level (p =
0.29).

It is thought that the distracted joint is less stiff when immobilized
for a shorter period of time. Six weeks of joint distraction has fewer pin
tract infections, at least among patients undergoing knee distraction. Another
important factor of decreasing the distraction period is that it reduces the
burden of immobilization and returning visits for patients. Therefore, the
treatment of knee distraction has been reduced to a period of 6 weeks nowadays.
Spaans et al. published the only available study on CMC1 joint distraction,
they had a sample size of 5 patients with a distraction duration of 8 weeks.
(9) It is unknown if six weeks of distraction is also sufficient for clinical
improvements among patients with symptoms of CMC1 OA.

To assess disability more efficiently with less burden on the patient,
the National Institutes of Health has developed the Patient Reported Outcomes
Measurement Information System (PROMIS) Physical Function-an instrument based
on item response theory. (17,18) The PROMIS PF Upper Extremity (UE) correlates
with DASH scores while taking less time to complete. (19,20) There is also
strong evidence that psychosocial factors (mindset and coping strategies)
influence and determine the intensity of symptoms and the magnitude of
limitations, also among patients with CMC1 OA. (21-24) Previous studies show
that patients with fewer CMC1 OA related symptoms have less catastrophic
thinking, and fewer depressive symptoms. (25,26) Catastrophic thinking can be
measured on a short 4-item questionnaire, the Pain Catastrophizing Scale.
(27,28) The 2-item Patient Health Questionnaire (PHQ-2) gauges symptoms of
depression. However, little is known about these psychosocial factors among
patients undergoing distraction therapy for CMC1 OA-related symptoms.

Therefore, this study tested the primary null hypothesis that there is
no difference in PROMIS PF UE SF at 1 year after 6 or 8 weeks of first
carpometacarpal joint distraction. Secondly, we tested that there is no
difference in 1) MHQ, VAS pain, range of motion, strength, and stiffness at 12
months posttreatment, and 2) minimal joint space width measured on X-rays at 1
year. We also assessed factors associated with PROMIS PF UE SF and MHQ scores
at 1 year, including patient characteristics and PHQ-2 and PCS-4.

Primary Hypothesis:
- There is a difference in PROMIS Physical Function Upper Extremity Short Form
(PROMIS PF UE SF) score between group A (6 weeks distraction) and group B (8
weeks distraction) at 1 year after first carpometacarpal joint distraction.

Secondary Hypotheses:
- There is no difference between group A (6 weeks distraction) and group B (8
weeks distraction) in MHQ, VAS pain, VAS satisfaction, VAS function, VAS
stiffness, range of motion, and strength at 1 year after CMC1 joint distraction.
- There is no difference in minimal joint space width measured on X-rays at 1
year between group A (6 weeks distraction) and group B (8 weeks distraction).
- There are no factors associated with PROMIS PF UE SF and MHQ at 1 year,
including patient characteristics, PHQ-2 and PCS-4.

Randomized Controlled Non-Inferiority Trial with a total of 68 patients divided
into two groups of 34 patients. Group A will undergo 6 weeks of joint
distraction. Group B will undergo 8 weeks of joint distraction.

Clinic visits
Patients will be requested to visit the outpatient clinic halfway during the
distraction therapy (at
3 or 4 weeks) and 3 months, 6 months, 1, 2 and 5 years postoperatively.
During these visits, patients will be invited to complete PROMIS PF UE SF, MHQ,
VAS pain, VAS satisfaction, VAS function, VAS stiffness, PHQ-2, PCS-4.The hand
therapist will perform measurements of strength and range of motion.

Surgical treatment and postoperative care
Added burden associated with study participation is the distractor presence of
six weeks
for patients in group A and eight weeks of patients in group B. A potential
risk is that of
disappointing results of the distractor treatment. In these cases, the
initially indicated invasive
surgical procedure can still be performed, albeit with delay caused by study
participation.
Standard X-ray imaging will be done at office visits pre-operatively,
perioperatively, during
distraction therapy (at 3 or 4 weeks), after distractor removal (at 6 or 8
weeks), and 3 months,
6 months, 1, 2 and 5 years postoperatively. The radiation burden will be
0.02mSv per X-ray, resulting in a total amount 0.16mSv. In our opinion this is
an acceptable small amount. The patient burden and the associated risks are
minimal.

Complications associated with distractor treatment
Participation risks are associated with the placement and presence of the
distractor device.
The first study of CMC1 joint distraction included five patients and only
reported one superficial
pin tract infection that could be managed with oral antibiotics. No technical
problems related
to the device were seen (9). All potential complications are expected to occur
in
the same prevalence as those known for established therapies such as metacarpal
bone
distraction or external fixation of comminuted fractures of the hand. These
potential
complications include:
1. pin tract infections. Incidence of pin tract infections in hand fractures is
6% according to the literature (31, 32). Two different classification systems
exists for describing the gravity of the infection and the best treatment (28,
29). Patients will be educated daily distractor hygiene routines (30). At
clinic visits the presence of infections is evaluated. In the very unlikely
case of a severely neglected pin tract infection, progression into
osteomyelitis of the trapezium or first metacarpal could occur. Early and
established pin tract infections can be adequately treated with oral and local
antibiotics.
2. loosening or dislodging of the device due to direct external forces. To
prevent snagging or bumping of the distractor device, a customized
thermoplastic splint is fashioned directly after placement of the device to
provide cover and protection. If for any reason the device is loosened or
dislodged, re-fixation or removal will follow varying per case.
3. technical problems with the distractor device. In 4 patients the K-wires
broke during removal of the distractor device in the outpatient clinic,
resulting in a small fragment of K-wire in situ in the trapezium bone. An
expectative therapy was initiated. Nowadays different K-wires are used and so
far no technical problems related to the device are seen in the last 2 years.
4. disappointing result. In case distraction therapy of either 6 or 8 weeks
yields insufficient results, the established options of invasive surgery will
still be possible. Study participation is not expected to influence results of
the chosen invasive surgery procedure, albeit the timing procedure will have
been postponed for study participation.