Stability with a Constrained Posterior Stabilized Primary Total Knee Arthroplasty Does Not Compromise Durability

Total knee arthroplasty (TKA) in cases of complex deformity (e.g., ligamentous laxity, posttraumatic arthritis) may require prostheses with inherent varus-valgus stability greater than that of traditional posterior stabilized or cruciate-retaining implants. Here, we investigate the clinical and radiographic outcomes of TKA using a midlevel constraint (MLC) prosthesis. A retrospective review of 53 patients (62 knees) who underwent primary TKA with an MLC implant was performed. Short tibial stem extensions were utilized in 49 knees, and 13 knees received no stem extension. Mean follow-up time was 31.6 months (standard deviation [SD] = 10.0, range = 24-53). Preoperative and postoperative range of motion (ROM) were assessed. Plain radiographs were reviewed for alignment, radiolucent lines, component loosening, and osteolysis. Patients who developed postoperative arthrofibrosis underwent manipulation under anesthesia (MUA). Failure was defined as instability, component loosening, or need for revision surgery. Mean ROM significantly improved from 114.1 degrees (SD = 19.7 degrees) preoperatively to 123.5 degrees (SD = 12.2 degrees) at final follow-up (t = -3.43, p = 0.001). Thirty-seven knees initially presented with varus deformity (mean = 7.5 degrees, SD = 4.8 degrees), whereas 23 had valgus deformity (mean = 10.6 degrees, SD = 6.5 degrees), and 2 knees had neutral alignment. Following surgery, mean alignment was 4.3 degrees valgus (SD = 1.7 degrees, range = 0-8 degrees), representing a statistically significant improvement (t = 5.29, p < 0.001). Six patients (9.7%) developed arthrofibrosis requiring MUA, which was irrespective of baseline ROM (p = 0.92) and consistent with 12% incidence reported in the literature. There were no significant differences in postoperative ROM (t = 0.38, p = 0.71), alignment (t = -0.22, p = 0.83), or incidence of arthrofibrosis (χ² = 0.07, p = 0.79) between short-stemmed and nonstemmed implants. There was no radiographic evidence of radiolucent lines, component loosening, or osteolysis in any patients. No patients required revision surgery. Use of an MLC prosthesis with primary femoral component in TKA resulted in satisfactory clinical and radiographic results with no evidence of component loosening, osteolysis, instability, or need for revision at minimum 2-year follow-up.

Cementless versus Cemented Fixation in Total Knee Arthroplasty

Despite the success of total knee arthroplasty (TKA), more than 20,000 revision TKA procedures are performed annually. In an effort to decrease failures due to loosening in the past, cementless fixation of TKA was suggested. The preliminary results of cementless fixation for TKA proved to be discouraging, with midterm results linking the use of uncemented components to early aseptic loosening. While cemented TKA has remained the gold standard fixation technique, the changing demographics of the average TKA patient have led some surgeons to revisit cementless fixation as an option.

A Modern Approach to Preventing Prosthetic Joint Infections

Total knee arthroplasty (TKA) is recognized as one of the most successful surgical procedures performed today. One of the most common and dreaded complications of TKA is postoperative infection. To prevent infections, it is critical to identify patients at high risk through analyzing their risk factors, and help in addressing them prior to surgery. The effort to prevent infection must be carried through every step of the surgical process, from preoperative counseling to intraoperative measures and postoperative protocols. Hair removal, the application of antiseptics, the utilization of antibiotics, barbed sutures, smart dressings, and antibacterial washes are some of the avenues surgeons may explore to help prevent infection.

Elevated intracranial pressure and reversible eye-tracking changes detected while viewing a film clip

OBJECTIVE The precise threshold differentiating normal and elevated intracranial pressure (ICP) is variable among individuals. In the context of several pathophysiological conditions, elevated ICP leads to abnormalities in global cerebral functioning and impacts the function of cranial nerves (CNs), either or both of which may contribute to ocular dysmotility. The purpose of this study was to assess the impact of elevated ICP on eye-tracking performed while patients were watching a short film clip. METHODS Awake patients requiring placement of an ICP monitor for clinical purposes underwent eye tracking while watching a 220-second continuously playing video moving around the perimeter of a viewing monitor. Pupil position was recorded at 500 Hz and metrics associated with each eye individually and both eyes together were calculated. Linear regression with generalized estimating equations was performed to test the association of eye-tracking metrics with changes in ICP. RESULTS Eye tracking was performed at ICP levels ranging from -3 to 30 mm Hg in 23 patients (12 women, 11 men, mean age 46.8 years) on 55 separate occasions. Eye-tracking measures correlating with CN function linearly decreased with increasing ICP (p < 0.001). Measures for CN VI were most prominently affected. The area under the curve (AUC) for eye-tracking metrics to discriminate between ICP < 12 and ≥ 12 mm Hg was 0.798. To discriminate an ICP < 15 from ≥ 15 mm Hg the AUC was 0.833, and to discriminate ICP < 20 from ≥ 20 mm Hg the AUC was 0.889. CONCLUSIONS Increasingly elevated ICP was associated with increasingly abnormal eye tracking detected while patients were watching a short film clip. These results suggest that eye tracking may be used as a noninvasive, automatable means to quantitate the physiological impact of elevated ICP, which has clinical application for assessment of shunt malfunction, pseudotumor cerebri, concussion, and prevention of second-impact syndrome.