Antiepileptic therapy, osteomalacia, and synchronous fractures: Don't lose looser zones.

Dear Editor,

We read with great interest the review article entitled “Impact of antiepileptic drugs on bone health: Need for monitoring, treatment, and prevention strategies.” It indeed is thorough and touches key aspects of the subject in its entirety. We would, however, like to add an often neglected aspect of prolonged therapy and concomitant osteopenia through a brief description of a case that made us learn a lesson and refresh our checklist while dealing with these cases in future. As orthopedic surgeons, we usually tackle fractures associated with decrease bone mass but synchronous fractures in our patient as we later understood was preventable to certain extent and so was agony of the patient and family. We believe this wisdom has potential to educate primary care doctors or healthcare worker for better anticipation of complication followed by due management or relevant referral.

A 15-year-old female child, a known case of generalized tonic–clonic seizures and on antiepileptic treatment since 6 years of age, presented with acute pain, swelling, and difficulty in weight bearing over right lower extremity following a bout of seizure last night. The radiographs confirmed subtrochanteric fracture of right side along with features of generalized osteomalacia such as trefoil-shaped pelvis, multiple looser zones in scapula, and an old clavicle fracture. There was a looser zone at medial femoral cortex on opposite side [Figure 1]. The present fracture itself appeared through a similar looser zone which propagated into full blown displaced fracture during seizure. On the following night, another bout of seizure led to pain on left side and identical fracture corresponding to the looser zone on that side [Figure 2]. The case was later managed successfully with fixation with flexible nails and led to gradual union in follow-up [Figure 3].

Figure 1

Right side femur fracture possibly through the looser zone. The presence of looser zone on contralateral side (arrow)

Figure 2

Fracture on left side few hours later following bout of seizure through the aforementioned looser zone

Figure 3

Radiograph showing fixation and uniting fractures with callus formation

Osteomalacia and associated looser zones can act as stress concentrator that may propagate into fractures during increased physiological stresses such as during seizure. Prolonged antiepileptic therapy along with decreased bone strength compounds the problem. Anticonvulsant therapy itself has been attributed to decrease bone strength.[1] Case–control studies have shown long-term antiepileptic drugs as contributing factor to risk of fractures more so in female patients.[2] The propagation of looser zones into fracture due to seizure is a rare occurrence more so if synchronous. Providing due prophylactic support or preferably fixation of long bones with radiologically visible looser zone is the lesson we learnt hard way in this case. Apart from it, ensuring appropriate nutrition, exercises along with calcium and Vitamin D supplementation.

Appropriate calcium through diet or supplements and Vitamin D with or without oral bisphosphonate therapy has been linked with improved bone health in such scenario.[34] The case highlights important lessons in the patient care when dealing with cases of seizure disorders with looser zones to observe caution for potential fractures with prophylactic splinting and periodic evaluation.

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