By Michael Rubin, MD

Professor of Clinical Neurology, Weill Cornell Medical College

Dr. Rubin reports he is a consultant for Merck Sharp & Dohme Corp.

SYNOPSIS: In a large series of cases from the Mayo Clinic, 54 cases of new neuropathy occurred in 14,450 total knee arthroplasties. Most were isolated peroneal neuropathies. No specific risk factors were identified.

SOURCE: Speelziek SJA, Staff NP, Johnson RL, et al. Clinical spectrum of neuropathy after primary total knee arthroplasty: A series of 54 cases. Muscle Nerve 2019;59:679-682.

Total knee arthroplasty (TKA) is expected to reach 2,854 procedures per 100,000 population by 2050. Although it is considered safe and effective for end-stage arthritis of the knee, complications occur during and after TKA, including myocardial infarction, thromboembolism, tourniquet-related ischemic injury, arterial injury, and neuropathy, most commonly peroneal nerve palsy. What is the spectrum and frequency of neuropathy following TKA, what are their clinical and electrophysiological features, and what is their mechanism of injury (mechanical, inflammatory, or both)?

In a retrospective review, Speelziek et al identified all patients ≥ 18 years of age who underwent TKA at Mayo Clinic Rochester between Jan. 1, 1996, and Sept. 30, 2016, and developed neuropathy within eight weeks of surgery. Exclusionary criteria included patients with pre-existing neuropathy, active radiculopathy, or central nervous system issues, which precluded accurate examination and evaluation. The review encompassed anesthesia type; findings on clinical, electrophysiologic, and radiologic studies; tourniquet time; and time to motor recovery. Among 14,450 TKAs performed during the study period, 54 instances of new neuropathy were identified in 53 patients, for a neuropathy incidence of 0.37%. Mean age was 65.2 years; 41 patients were female; postoperative day 2 was the mean time of neuropathy symptom onset (with a range of 0-28 days); and almost all were mononeuropathies of the ipsilateral limb (with one patient exhibiting both peroneal and tibial mononeuropathies). Over a mean of 10.1 months, but ranging from two to 136 months, complete or almost complete recovery occurred in all but one patient who appreciated no recovery. Four patients were lost to follow-up.

Peroneal neuropathy, presenting as foot drop, nonfocal in eight of 10 patients studied electrodiagnostically, was the most common form of post-TKA neuropathy, seen in 37 patients, followed by sciatic neuropathy in 11, tibial or ulnar neuropathy in two patients each, and sural or lumbosacral plexopathy in one patient each. Sciatic neuropathy was localized proximal to the short head of biceps femoris in four studies and distally in three studies, with two studies limited to nerve conduction studies only, precluding localization, and one additional study that was normal. Tibial neuropathy presented with tingling or hyperesthesia of the sole or toes, with impaired Achilles reflex and ankle inversion weakness. Diffuse progressive neuropathic pain and weakness of the ipsilateral leg were the features of the single instance of post-TKA lumbosacral plexopathy. A 67-year-old woman responded to IV methylprednisolone after she was refractory to opiates, with significant improvement over the treatment period. Overall, for tourniquet time longer than 100 minutes (a time generally associated with an increased risk of complications), mean motor recovery time was 11.8 months, ranging from 7.9-15.7 months. For tourniquet time less than 100 minutes, mean motor recovery time was 8.1 months, ranging from 5.1-11.0 months, a nonsignificant difference due to a large standard deviation in each group. No correlation with type of anesthesia was evident. Inflammatory origin of post-TKA neuropathy, as evidenced by the single instance of lumbosacral plexopathy, was extremely rare.

COMMENTARY

Combined general and spinal epidural anesthesia is used commonly for bilateral TKA, with accidental dural puncture occurring in 0.19-3.6%. Cranial nerve palsy is a rare complication of dural puncture, but both abducens nerve palsy and oculomotor nerve palsy have been reported following accidental dural puncture during bilateral total knee replacement. In either instance, reassurance of the patient is important as most cranial nerve palsies following dural puncture resolve within one to four weeks. Following total hip arthroplasty, foot drop also is the most common neurologic complication, but due to sciatic nerve injury, with the peroneal division more commonly and severely affected than the tibial.