Case Report: Why might this 52-year-old lady be prone to osteoporosis?

The 52-year-old woman in front of me had been wheelchair-bound by her cancer for over a year.The referral was odd, coming to the office rather than through the regional CritiCall system. “Please see re: unknown spine cancer/almost paraplegic.” It didn’t make sense. Something to see in the controlled environment of my office where I can think rather than in the overburdened chaos of the hospital clinic.The patient had been previously well, a small slim lady who’d actually quit smoking to celebrate turning 50. That winter she had a slip-and-fall and came down hard on her rump, hurting enough to need help getting up and hobbling after. A constant deep aching pain at the base of her low back set in quite quickly and was aggravated by activity such that she needed a cane right away.The family doctor prescribed anti-inflammatories and Tylenol, then codeine and even Percocet didn’t help. Her chiropractor couldn’t help either and when a physiotherapist tried to manipulate her spine back into alignment the pain got suddenly worse and she started using the wheelchair.Her appetite dropped off and she was tortured when the meds constipated her. It hurt to push at a bowel movement. Bladder control was normal. Being so inactive her weight ballooned up to almost twice her original 90 pounds and so she felt even more miserable.And she was scared—what’s going on? The chiropractor’s X-ray of her low back hadn’t shown anything so she had the family doctor repeat them at the hospital, no change. She’d asked for a scan after the X-rays but the doctor was initially reluctant to order the expensive test because common teaching is that back pain gets better and scans are useless—but this wasn’t acute. Only when she went into the wheelchair did the family doctor relent and order a CT scan of the low back to be done at the local community hospital, old technology and very radiation-intensive (one spine CT delivers the equivalent radiation dose of 600 chest X-rays).The scan didn’t show a problem in the lumbar spine of her low back but the pelvis below looked a bit off and the radiologists suggested another CT, this time of the pelvis. Pay dirt!It showed that the sacrum was riddled through with several fracture lines.The lumbar vertebrae rest on the triangular sacrum, a bone about the size of a large man’s fist that spans the gap between your waistline and your anus between the gluteus muscles of your rear end. It functions a lot like the keystone of the pelvic arch. This bone transmits weight from the low back to the sacroiliac joints and thus through the pelvis to your legs. It’s an odd bone in that much of its internal structure is largely hollow but its surfaces are very hard and strong, they have to be to transmit the weight.Being the keystone of the pelvis, all the ligaments that support the pelvic floor and lower organs there (like the bladder and rectum) are also attached to the sacrum.Sacral fractures can effectively disconnect all that viscera from your skeleton, and the patient often can’t control the bowels or bladder at all because there’s no firm foundation to push against.Bones don’t break easily in healthy middle-aged people and when they do they generally don’t shatter into several pieces unless there was a great deal of energy involved, like a car crash. This was just a slip-and-fall. If a low energy injury shows a high-energy fracture morphology something has to be wrong within the bone—and so, common things being common, the radiologist diagnosed a cancer.But what kind, from where? Spine cancers in adults are generally known to be metastatic but this lady had no cancer history herself nor in her family. The scan didn’t show a distinctive lesion for biopsy and so the cancer center did a standard workup looking at the common source “paired organs” being the thyroid (a blood test), lungs (chest X-ray or CT), breasts in a lady (mammogram). Guys get a PSA test for the prostate. Bloodwork for renal function. Unpaired source organs include the gut from stomach to rectum (that’s another CT scan), the bone marrow (serum protein electrophoresis and a 24-hour urine for Bence Jones protein), and the skin (that’s a visual inspection for melanoma). They also did a nuclear medicine bone scan to look for other potential sites of cancer in the skeleton. All negative.So, back to the sacrum and an interventional radiologist took several core biopsies under CT guidance. The biospsies did not confirm a cancer but showed a mix of dead bone and fibrous tissue that looked a lot like a fracture. So she’s sent to my office by the cancer center for a surgical biopsy before they started the radiation therapy they’d decided on.Reviewing all her X-rays was a struggle, for some reason they seemed very washed out and ghostly to look at no matter how I fiddled with my imaging software. The CT scans were of better quality and showed two vertical fractures running vertically along the sacral ala and a smaller horizontal one running through the vestigial S2 body, breaking up what should be one strong solid bone into four fragments.This fracture pattern is distinctive to what’s called a fatigue fracture. There are two types, stress fracture or insufficiency fracture. Stress fractures happen when normally strong bone is subjected to regular and repeated high loads, like when you take up a new sport or heavy job and overdo it. Insufficiency is when normal loads overwhelm relatively soft bone, such as bone eroded by a cancer. Or, osteoporosis.There’s a classical principle in orthopedics called “Wolff’s Law” that states bone responds to load and will be deposited where needed in the body and resorbed where it is not. So big heavy people and those who lift and carry things a lot have stronger harder bone than inactive people, that’s why seniors commonly get osteoporosis. Calcium moves out of inactive bone quite quickly, so much so that when I was a student we had to acidify the urine in bedridden ICU patients to prevent them from getting kidney stones all the time. When young people have a minor broken ankle managed in a walking splint the X-ray at six weeks the bone’s calcium is always washed out to look at—though in these fit active young people it recalcifies quickly. If we take another film after a month or two of physio all is usually well.I ordered a DEXA scan to confirm the diagnosis and a vitamin D blood level as we know most Canadians are deficient in that bone-critical vitamin that comes to us through skin exposure to the sun, we just don’t get enough sunlight in the Northern climate. Meanwhile I started her on some vitamin D tablets, that can’t hurt—Health Canada actually recommends we all start taking 1,000 units daily at the age of 40 to stave off osteoporosis. Last I wanted an MRI on the off chance I was wrong and there is a tumour in there that the older CT technology might have missed.Two of three tests come back positive. Her bone density is formally osteoporotic, her vitamin D level just at the lowerlevel of normal. The MRI shows no cancer.Why might this lady be prone to osteoporosis? Remember her normal body weight was just 90 pounds. Weighing less than 110 pounds is a major risk factor for osteoporosis in women, by Wolff’s Law they can’t load enough to calcify well. And, she was an ex-smoker. Nicotine is just about poison for your bones, being associated both with osteoporosis and with delayed or incomplete fracture healing.After considering all this, I had to decide what to do with the lady. She had a problem where the load being applied to her bone, even being chairbound, exceeded the ability of the bone to carry it. So, one either decreases the load or strengthens the bone.She had already decreased the load as much as can be expected, short of going to complete 24/7 bedrest which just isn’t practical even if it didn’t bring on great risk of many serious complications.We could offload the bone surgically with an instrumentation operation where bone screws are anchored into the spine and iliac wings of the pelvis and then connected by rods that carry load past the sacrum. That’s done commonly for violent fracture injuries but not so much in osteoporosis cases where the screws are not likely to hold well in the soft bone.Strengthening the bone can be done with bone cement injections in an operative procedure called “sacroplasty.” It’s not done commonly and best suited to distinct voids in the bone such as those eaten away by a cancer. On top of it all there are important nerve roots running through the sacrum that are involved in bowel and bladder control, and the cement can injure them. Beyond that, it routinely takes a good year if not two for a Canadian patient to access elective spine surgical care, there was a lot of waiting list ahead of her.Because of that waiting list, I offered the procedures (I’d propose to do both at one sitting) at her first visit and she tearfully gave me consent, finally seeing some hope.While she’d be working her way up that list it made sense to try another option in to strengthen the bone, prescribing a bisphospohonate. These work by shutting down the bone-resorbing side of Wolff’s Law, inhibiting osteoclast function. With these, gains in bone density run 3%-4% per year at best.One osteoporosis drug very uniquely drives osteoblast function. Teriparatide isn’t really a drug at all but a cloned fragment of Parathyroid Hormone that is a major controller of bone formation. It can drive bone density up two to three times faster than the alternatives and is really exciting for surgeons like me who frequently deal with osteoporosis patients. Sadly it’s not generally an option for many Canadian patients because the state won’t pay for it without very specific indications and it is quite expensive. Another drawback is that as a protein hormone it can’t be administered as a pill. It’s an injection you give yourself once a day, and people don’t like to do that.She had some insurance and was willing to pay out to get her life back if need be. We ordered the drug, and after six weeks or so of back-and-forth with the supplier she started on it.A month later she wheelchaired back into my office for my routine how-is-the-drug visit, tolerating it well butfrustrated that she didn’t feel any better.Three months later she came in with the wheelchair but then stood and hobbled the few short steps to my consult suite with her walker. Yes it is possible for a person to grit their teeth and smile at the same time, she was better! I couldn’t be sure; she very much wanted to get better, and placebo effect is such that a third of patients will convince themselves they are better when they aren’t. So I ordered another pelvic scan, MRI to avoid all that radiation.Six weeks later the scan was astounding, the radiologists reported the fractures largely healed and even the patient could see it when I brought up the scan on the big monitor in my office. And she saw it after walking in to my office from the parking lot with a walker and then from waiting room to consult suite with just a cane.This is a big win for me, and her. She was off my surgical waiting list, and went on to a full recovery, smiling a lot.Dr. Drew Bednar is a clinical professor of orthopedic surgery at McMaster University in Hamilton. This report is based on a real case from Dr. Bednar’s files.

Case Report: Why might this 52-year-old lady be prone to osteoporosis?

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