Spinal Anesthetic for Hip and Knee Replacement Surgery - Intrathecal Morphine or Hydromorphone

A significant increase in the number of patients receiving hip or knee replacements can be expected in the coming years, for two main reasons: an increase in the number of elderly patients in the society and the fact that joint replacements are offered to younger patients because of an improvement in materials, designs, and survivorship of prostheses in general. As a result, healthcare institutions are facing pressure to provide more services, while decreasing overall spending.

Hôpital Montfort is an important component of the healthcare structure in Ottawa and Eastern Ontario, providing hip or knee replacements to roughly 1200 patients every year. These include total hip and knee replacements, partial medial and lateral knee replacements, and patellafemoral replacements. Some partial knee replacement surgeries are bilateral, meaning both knees are operated at the same sitting.An increase in the demand for joint replacements is expected. This will follow the national trend of the last 5 years (2012-2017): 17.8% increase in hip replacements and 15.5% increase in knee replacements. This in turn will continue to place an unbearable financial burden on the healthcare system, as implanted components are very expensive. Furthermore, patients undergoing joint replacement also often require the use of ancillary services such as physiotherapy, occupational therapy, and inpatient rehabilitation. However, the healthcare system is under tremendous strain, as budgets can no longer allow previous levels of spending. It is this current economic context that is forcing healthcare professionals to find ways to decrease costs as much as possible, while maintaining productivity.

Over 95% of joint replacements at Hôpital Montfort are performed under spinal anesthetic. Intrathecal morphine is added to standard anesthetic medication for better immediate post-operative pain control, which in turn facilitates rapid patient mobilization. However, most orthopedic surgeons would prefer to avoid morphine, because of a recognized higher incidence of post-operative side-effects, mainly urinary retention, nausea, and vomiting. It is very difficult to send patients home when they cannot urinate, tolerate oral intake, or mobilize safely. Patients who experience one of these post-operative complications stay in hospital. Discharging these patients home can be unsafe, but also leads to patient dissatisfaction, and the perception of uncaring and unsympathetic care. Many patients do not understand the financial implications of a prolonged stay in hospital, and expect that they can stay as long as they want.

A medication that can meet all our patients' needs: effective analgesia, early mobilization, and minimal negative side effects, is still to be found, so patients can go home sooner, The anesthesia literature seems to indicate that hydromorphone might be the right choice, but no study compared intrathecal morphine and hydromorphone usage in the adult population.

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