Delayed Onset of Peroneal Nerve Palsy After Total Knee Arthroplasty.

Peroneal nerve palsy (PNP) and peroneal nerve dysfunction (PND) are rare complications after total knee arthroplasty (TKA). Although PND tends to manifest as transient lateral leg paresthesias that are associated with knee motion, PNP has characteristic motor deficits, including loss of ankle dorsiflexion and eversion strength. Although PND can manifest days, weeks, or months after surgery, delayed cases of PNP have not been well documented. We describe a 72-year-old woman with a delayed case of sudden-onset PNP 10 weeks after TKA. She had no neurologic deficits preoperatively and was recovering uneventfully at 2 and 6 weeks postoperatively. At 10 weeks, she reported insidious onset of drop foot and sensory changes to the lateral leg and dorsum of the foot. Motor deficits included significant loss of ankle dorsiflexion and eversion strength. After a diagnosis of PNP was confirmed with electrodiagnostic studies and lumbar pathology was ruled out with lumbar magnetic resonance imaging, surgical decompression of the peroneal nerve was performed. By 7 weeks after surgical decompression, she had no sensory deficits and nearly full strength in ankle dorsiflexion and eversion. This case shows that PNP can occur several weeks to months outside of the currently documented timeline. Although PNP is an uncommon risk of TKA, it is important to recognize and treat it when it occurs among patients with significant motor and sensory deficits along the distribution of the peroneal nerve postoperatively. [Orthopedics. 2022;45(6):e342-e344.].

Load Sharing in the Femur Using Strut Allografts: A Biomechanical Study.

Background: Femoral strut allografts are used in revision hip arthroplasty for management of bone loss associated with implant failure or periprosthetic fractures. They have also been used to treat unremitting thigh pain in well-fixed cementless femoral stems, to address the differential in structural stiffness between the stem and femoral shaft. Our study used an in vitro biomechanical model to measure the effect of placement of allografts on femoral strains, to determine their load-sharing capacity. Material and methods: Three rosette strain gauges were applied to the femoral surface of each of 6 cadaveric femurs, at the stem tip level on anterior, medial, and lateral cortices. After stem implantation, cortical strut allografts were applied to the lateral femoral shaft and secured with 4 Dall-Miles cables. A fourth gauge was placed on the midpoint of the allograft. Strains were recorded in the intact femur, then the implanted femur with and without the allograft under simulated physiologic loading in a load frame. Results: Reduction in distal femoral principal strains, between 12% and 59%, was seen in all cortices following placement of the allograft. Under axial loading, 30% of the strain in the lateral cortex was borne by the allograft. Greater reductions in strain, by as much as 59%, occurred under axial load and torque. Conclusion: The results of this biomechanical model indicate that by placement of an allograft, cortical strains can be reduced to levels approaching those in an intact femur, supporting this technique for treatment of unremitting thigh pain in well-fixed prostheses.

Safety, Tolerability, and Effect on Opioid Use of Meloxicam IV Following Orthopedic Surgery.

OBJECTIVE: A Phase 3 randomized multicenter, double-blind, placebo-controlled trial (NCT02720692) compared once-daily intravenous (IV) meloxicam 30 mg to placebo, when added to the standard of care pain management regimens, in adults with moderate-to-severe pain following major elective surgery and concluded that meloxicam IV had a safety profile similar to placebo and reduced opioid consumption. METHODS: In this post hoc subgroup analysis of orthopedic surgery subjects, 379 subjects received meloxicam IV 30 mg or IV-administered placebo every 24 hrs for ≤7 doses. Safety was assessed via AEs, laboratory tests, vital signs, and ECG, with an emphasis on specific AEs, including injection site reactions, bleeding, cardiovascular, hepatic, renal, thrombotic, and wound healing events. Daily opioid consumption was assessed during treatment. RESULTS: Among meloxicam IV-treated subjects, 64.7% experienced ≥1 AE versus 68.8% of placebo-treated subjects. Investigators assessed most AEs to be mild or moderate in intensity and unrelated to treatment. Total opioid consumption (36.8 mg versus 50.3 mg IV morphine equivalent dose; P=0.0081) and opioid consumption during time points 0‒24, 24‒48, 0‒48, and 0‒72 hrs were statistically significantly lower in the meloxicam IV group. CONCLUSION: Meloxicam IV demonstrated no significant differences in the number and frequency of AEs versus placebo in subjects following orthopedic surgery. Opioid consumption was reduced in the meloxicam IV group versus placebo. TRIAL REGISTRATION: ClinicalTrials.gov (Identifier: NCT02720692).

Pseudotumor Formation in a Metal-on-polyethylene Total Hip Arthroplasty Due to Trunnionosis at the Head-neck Taper.

We present here a case of pseudotumor formation likely due to metal wear debris generated at the head-neck taper (trunnion) of the femoral stem and head components in a metal-on-polyethylene (MOP) total hip arthroplasty. Over the last few years, this recently described diagnosis, trunnionosis, has been recognized and reported more frequently. This patient presented with a rather large (12-cm diameter) pseudotumor with accompanying loss of abductors and a pelvic discontinuity making reconstruction more challenging. We believe the psuedotumor in this patient developed from trunnionosis. This is an interesting case of aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) in a MOP total hip arthroplasty.

Lack of early dislocation following total hip arthroplasty with a new dual mobility acetabular design.

Dual mobility implant designs minimise the risk of dislocation without sacrificing range of motion. Between 1st September 2008 and 31st July 2011, 5 institutions examined early clinical outcomes of a new dual mobility bearing hip system implanted in 485 primary THAs in 452 patients. Patient demographics were 46% female, a mean age of 67 years and a mean BMI of 30. Complications at a minimum of 2 years after surgery included 1 femur fracture, 1 DVT and 4 unrelated deaths. There were no dislocations. For functional outcomes, Harris Hip Scores increased from 41 to 86 (p<0.001), while VAS pain scores decreased from 5.9 to 0.7 (p<0.001). Minimal complications, excellent early clinical outcomes and the absence of early dislocations demonstrate the improved stability of this dual mobility implant system.