Medical Musings, Health Hypotheses & Therapeutic Thoughts
What is Frozen Shoulder Syndrome (FSS)
Almost everyone has heard of ‘frozen shoulder’, but very few have a good idea of what it entails. To be honest, even the medical profession understands what happens quite well, but not so much the why, even though it was first described in the eighteen hundreds [i], and affects about three to five percent of the population [ii] .
Frozen shoulder is a bit of a catch-all term, and when coined in the 1930’s, described a condition with slow-onset shoulder pain, inability to lie on the affected side, restricted movement of the arm (particularly lifting it or turning it outwards), and a normal radiologic appearance (that is, nothing discoverable on x-ray) [iii]. It has also been known as adhesive capsulitis, referring to the fibrous joint capsule surrounding the shoulder joint.
You may remember that to allow the shoulder to do everything it needs to, you need the bony joint surfaces and soft tissue structures to permit a lot of movement. This means that the capsule that surrounds the shoulder, or glenohumeral joint, is baggy, with lots of folds. The idea is (or was) that adhesions, or sticky bits, between the folds stopped the arm from moving as far as it could/should. However, the evidence for these capsular adhesions is a bit controversial, which is why we now ‘stick’ (Sorry! Couldn’t resist!) to the term “frozen shoulder.”
The current thinking is that is not an ‘adhered’ joint capsule, but rather a contractured one (‘contracture’ is the [?permanent] shortening or hardening of a muscle or joint). So rather than that nice baggy capsule with lots of loose folds that have stuck to each other, you have a sort of tightening, like shrink-wrap. We still don’t know why that might happen, though!
Anyway, the long and short of it is that we do not really know what causes frozen shoulder syndrome (FSS). As with many conditions, FSS can occur on its own, or as a result of other issues. The first is called primary or idiopathic frozen shoulder, whereas if it is associated with other diseases and conditions, it is called secondary frozen shoulder.
Causes of FSS
Despite the lack of any particularly compelling evidence to link frozen shoulder with any one particular factor, several issues are thought to trigger FSS:
Trauma such as a rotator cuff tear (see previous blog!), broken arm or even surgery – it should be noted that is [obviously] more common after shoulder surgery, but not limited to such.
Metabolic/endocrine/hormonal such as thyroid disease, diabetes mellitus and other auto-immune disorders, where the body’s own immune system naively but enthusiastically attacks things wrongly identified as intruders [iv],[v],[vi],[vii],[viii]. With female sufferers (whom are affected more than men), onset is often around the same time as the menopause, implying a hormonal link [ix].
Neurological issues such as stroke and Parkinson’s disease can also trigger FSS.
Heart problems such as ischaemic heart disease (not getting enough blood to the heart) and hypertension (high blood pressure) have also been implicated.
Drugs, for instance some antibiotics and antiretrovirals (and other drugs, such as the grandiosely-named protease inhibitors, used to treat HIV). Some people also report developing FSS after immunisations, such as influenza or pneuomococcus.
Probably the biggest factor that we know about is inactivity. Most patients with FSS have undergone some period of shoulder immobilization, for one reason or another. This may be one of the ways that surgery has an impact (you are normally asked to not move around too much immediately after an operation). One study looked at patients undergoing neurosurgery who had immobilized shoulders for various periods, and found that the incidence of FSS was 5-9 times greater than in the general population[x].
So, the typical presentation for frozen shoulder would be someone in their fifties or sixties (peak age of onset being mid-fifties), more likely to be a woman than a man, and with a history of one or more of the above-listed factors, likely involving not moving one or both arms for a prolonged period. Interestingly, the non-dominant shoulder is slightly more likely to be affected.
Symptoms of FSS
The symptoms of frozen shoulder have traditionally been divided into three phases, and given the catchy monikers of freezing, frozen, and thawing.
Freezing (Stage 1) is characterised by gradual onset of diffuse (widespread, difficult-to-localise) shoulder pain. This stage can last from weeks up to nine months or so, but a year is not unheard-of.
Frozen (Stage 2) constitutes a gradual, progressive loss of shoulder range of movement. You may find that it is not actually that painful in this stage, and the frustration comes more from not being able to bloody lift your arm than unremitting agony. Unfortunately, guys, this stage can last anywhere from a few months to nearly two years (four to twenty months would be a quoted figure).
Thawing (Stage 3) consists of a phase of gradually (but not necessarily constantly) increasing range of movement. This can also be a protracted stage, ranging from another few months (ok, around 4-5) to another couple of years (well, 26-odd months).
It is extremely rare to get frozen shoulder bilaterally (on both sides) at the same time (Thank goodness!), but around 6-17% of poor, limp-armed patients who have recently recovered from a bout of FSS will find an ominously-familiar ache in the other shoulder within five years, although recurrence in the same shoulder is unlikely[xi],[xii].
Next up I will discuss is the treatment options for Frozen Shoulder Syndrome (FSS)...
[i] Duplay S. De la periarthrite scapulo-humerale [On scapulo-humeral periarthritis]. Rev Pract D Trav De Med. 1896;53:226. French
[ii] Manske, R. & D. Prohaska, “Diagnosis and Management of of adhesive capsulitis” Curr Rev Musculoskelet Med. 2008 December; 1(3-4): 180–189
[iii] Codman, E.A. (1934) The Shoulder Thomas Todd: Boston, MA
[iv] Bulgen, D.Y., Binder, A., Hazleman B.L. et al (1982) “Immunological studies in frozen shoulder” Journal of Rheumatology 9(6):893-8
[v] Bulgen, D.Y., Hazleman B.L., & Voak, D. (1976) “HLA-B27 and frozen shoulder” Lancet 1(7968):1042-4
[vi] Morén-Hybbinette I, Moritz U, Scherstén B (1987) “the clinical picture of the painful diabetic shoulder--natural history, social consequences and analysis of concomitant hand syndrome” Acta Med Scand. 1987;221(1):73.
[vii] Lequesne M, Dang N, Bensasson M, Mery C (1977) “Increased association of diabetes mellitus with capsulitis of the shoulder and shoulder-hand syndrome” Scand J Rheumatol. 1977;6(1):53
[viii] Huang YP, Fann CY, Chiu YH, Yen MF, Chen LS, Chen HH, Pan SL (2013) “Association of diabetes mellitus with the risk of developing adhesive capsulitis of the shoulder: a longitudinal population-based followup study” Arthritis Care Res (Hoboken). 2013 Jul;65(7):1197-202.
[ix] Ewald, A. (2011) "Adhesive capsulitis: A review" American family physician 83(4):417–422
[x] Bruckner FE; Nye CJ (1981) “A prospective study of adhesive capsulitis of the shoulder ("frozen shoulder') in a high risk population” Q J Med. 1981; 50(198):191-204
[xi] Rizk TE, Pinals RS. “Frozen shoulder” Semin Arthritis Rheum. 1982;11:440–452.
[xii] Guyver PM, Bruce DJ, Rees JL “Frozen shoulder - A stiff problem that requires a flexible approach” Maturitas. 2014 May; 78(1):11-6.