David J. Mayman

Accelerometer-Based, Portable Navigation vs Imageless, Large-Console Computer-Assisted Navigation in Total Knee Arthroplasty: A Comparison of Radiographic Results

Computer-assisted surgery (CAS) systems improve alignment accuracy in total knee arthroplasty (TKA) but have not been widely implemented. Eighty knees underwent TKA using an accelerometer-based, portable navigation device (KneeAlign 2; OrthAlign Inc, Aliso Viejo, California), and the radiographic results were compared with 80 knees performed using a large-console, imageless CAS system (AchieveCAS; Smith and Nephew, Memphis, Tennessee). In the KneeAlign 2 cohort, 92.5% of patients had an alignment within 3° of a neutral mechanical axis (vs 86.3% with AchieveCAS, P < .01), 96.2% had a tibial component alignment within 2° of perpendicular to tibial mechanical axis (vs 97.5% with AchieveCAS, P = .8), and 94.9% had a femoral component alignment within 2° of perpendicular to the femoral mechanical axis (vs 92.5% with AchieveCAS, P < .01). The mean tourniquet time in the KneeAlign 2 cohort was 48.1 ± 10.2 minutes vs 54.1 ± 10.5 minutes in the AchieveCAS cohort (P < .01). Accelerometer-based, portable navigation is as accurate as large-console, imageless CAS systems in TKA.

An Articulating Spacer to Treat and Mobilize Patients with Infected Total Knee Arthroplasty

This retrospective study analyzed 25 consecutive patients (25 knees) with chronic deep TKA infection. During 1997-2004, patients underwent two-stage articulating spacer surgery. The original femoral component was removed, autoclaved and replaced and a new polyethylene was utilized. The second- stage procedure occurred at a mean of 11 weeks (range: 4 to 39 weeks) after spacer insertion. Mobilization was encouraged between stages. All patients were assessed at a minimum of two years (mean 54 months; range: 24-108 months) post re-implantation, and Modified Hospital for Special Surgery (HSS) knee scores were calculated. Only one patient (4%) had re-infection. Average ROM before re-implantation was 5 degrees to 112 degrees , and 3 degrees to 115 degrees at latest follow-up. HSS scores averaged 91 (Range: 65-100) at latest follow-up. Two-stage re-implantation with an articulating spacer for infected TKA effectively treats infection and gives excellent knee motion between stages, and at mid- to long-term follow-up.

Pelvic Tilt in Patients Undergoing Total Hip Arthroplasty: When Does it Matter?

Pelvic tilt (PT) affects the functional anteversion and inclination of acetabular components in total hip arthroplasty (THA). One-hundred and thirty-eight consecutive patients who underwent unilateral primary THA were reviewed. Most cases had some degree of pre-operative PT, with 17% having greater than 10° of PT on standing pre-operative radiographs. There was no significant change in PT following THA. A computer model of a hemispheric acetabular component implanted in a range of anatomic positions in a pelvis with varying PT was created to determine the effects of PT on functional anteversion and inclination. Based on the study results, tilt-adjustment of the acetabular component position based on standing pre-operative imaging will likely improve functional component position in most patients undergoing THA.

A prospective, multi-center, randomised trial to evaluate the efficacy of a cryopneumatic device on total knee arthroplasty recovery

Pain, swelling and inflammation are expected during the recovery from total knee arthroplasty (TKA) surgery. The severity of these factors and how a patient copes with them may determine the ultimate outcome of a TKA. Cryotherapy and compression are frequently used modalities to mitigate these commonly experienced sequelae. However, their effect on range of motion, functional testing, and narcotic consumption has not been well-studied. A prospective, multi-center, randomised trial was conducted to evaluate the effect of a cryopneumatic device on post-operative TKA recovery. Patients were randomised to treatment with a cryopneumatic device or ice with static compression. A total of 280 patients were enrolled at 11 international sites. Both treatments were initiated within three hours post-operation and used at least four times per day for two weeks. The cryopneumatic device was titrated for cooling and pressure by the patient to their comfort level. Patients were evaluated by physical therapists blinded to the treatment arm. Range of motion (ROM), knee girth, six minute walk test (6MWT) and timed up and go test (TUG) were measured pre-operatively, two- and six-weeks post-operatively. A visual analog pain score and narcotic consumption was also measured post-operatively. At two weeks post-operatively, both the treatment and control groups had diminished ROM and function compared to pre-operatively. Both groups had increased knee girth compared to pre- operatively. There was no significant difference in ROM, 6MWT, TUG, or knee girth between the 2 groups. We did find a significantly lower amount of narcotic consumption (509 mg morphine equivalents) in the treatment group compared with the control group (680 mg morphine equivalents) at up to two weeks postop, when the cryopneumatic device was being used (p < 0.05). Between two and six weeks, there was no difference in the total amount of narcotics consumed between the two groups. At six weeks, there was a trend toward a greater distance walked in the 6MWT in the treatment group (29.4 meters versus 7.9 meters, p = 0.13). There was a significant difference in the satisfaction scores of patients with their cooling regimen, with greater satisfaction in the treatment group (p < 0.0001). There was no difference in ROM, TUG, VAS, or knee girth at six weeks. There was no difference in adverse events or compliance between the two groups. A cryopneumatic device used after TKA appeared to decrease the need for narcotic medication from hospital discharge to 2 weeks post-operatively. There was also a trend toward a greater distance walked in the 6MWT. Patient satisfaction with the cryopneumatic cooling regimen was significantly higher than with the control treatment.

Ideal femoral head size in total hip arthroplasty balances stability and volumetric wear.

BackgroundOver the last several years, a trend towards increasing femoral head size in total hip arthroplasty to improve stability and impingement free range of motion has been observed.PurposeThe specific questions we sought to answer in our review were: (1) What are the potential advantages and disadvantages of metal-on-metal, ceramic-on-ceramic, and metal-on-polyethylene bearings? (2) What is effect that femoral head size has on joint kinematics? (3) What is the effect that large femoral heads have on bearing surface wear?MethodsA PubMed search and a review of 2012 Orthopaedic Research Society abstracts was performed and articles were chosen that directly answered components of the specific aims and that reported outcomes with contemporary implant designs or materials.ResultsA review of the literature suggests that increasing femoral head size decreases the risk of postoperative dislocation and improves impingement free range of motion; however, volumetric wear increases with large femoral heads on polyethylene and increases corrosion of the stem in large metal-on-metal modular total hip arthroplasty (THA); however, the risk of potentially developing osteolysis or adverse reactions to metal debris respectively is still unknown. Further, the effect of large femoral heads with ceramic-on-ceramic THA is unclear, due to limited availability and published data.ConclusionsSurgeons must balance the benefits of larger head size with the increased risk of volumetric wear when determining the appropriate head size for a given patient.

Use of Hip Arthroscopy and Risk of Conversion to Total Hip Arthroplasty: A Population-Based Analysis

PURPOSE To use population-level data to (1) evaluate the conversion rate of total hip arthroplasty (THA) within 2 years of hip arthroscopy and (2) assess the influence of age, arthritis, and obesity on the rate of conversion to THA. METHODS We used the State Ambulatory Surgery Databases and State Inpatient Databases for California and Florida from 2005 through 2012, which contain 100% of patient visits. Hip arthroscopy patients were tracked for subsequent primary THA within 2 years. Out-of-state patients and patients with less than 2 years follow-up were excluded. Multivariate analysis identified risks for subsequent hip arthroplasty after arthroscopy. RESULTS We identified 7,351 patients who underwent hip arthroscopy with 2 years follow-up. The mean age was 43.9 ± 13.7 years, and 58.8% were female patients. Overall, 11.7% of patients underwent THA conversion within 2 years. The conversion rate was lowest in patients aged younger than 40 years (3.0%) and highest in the 60- to 69-year-old group (35.0%) (P < .001). We found an increased risk of THA conversion in older patients and in patients with osteoarthritis or obesity at the time of hip arthroscopy. Patients treated at high-volume hip arthroscopy centers had a lower THA conversion rate than those treated at low-volume centers (15.1% v 9.7%, P < .001). CONCLUSIONS Hip arthroscopy is performed in patients of various ages, including middle-aged and elderly patients. Older patients have a higher rate of conversion to THA, as do patients with osteoarthritis or obesity. LEVEL OF EVIDENCE Level III, retrospective comparative study.

Extramedullary Guides Versus Portable, Accelerometer-Based Navigation for Tibial Alignment in Total Knee Arthroplasty: A Randomized, Controlled Trial: Winner of the 2013 HAP PAUL Award

Extramedullary (EM) tibial alignment guides have demonstrated a limited degree of accuracy in total knee arthroplasty (TKA). The purpose of this study was to compare the tibial component alignment obtained using a portable, accelerometer-based navigation device versus EM alignment guides. One hundred patients were enrolled in this prospective, randomized controlled study to receive a TKA using either the navigation device, or an EM guide. Standing AP hip-to-ankle and lateral knee-to-ankle radiographs were obtained at the first, postoperative visit. 95.7% of tibial components in the navigation cohort were within 2° of perpendicular to the tibial mechanical axis, versus 68.1% in the EM cohort (P<0.001). 95.0% of tibial components in the navigation cohort were within 2° of a 3° posterior slope, versus 72.1% in the EM cohort (P=0.007). A portable, accelerometer-based navigation device decreases outliers in tibial component alignment compared to conventional, EM alignment guides in TKA.

Ceramic Liner Fractures Presenting as Squeaking After Primary Total Hip Arthroplasty

BACKGROUND Squeaking after ceramic-on-ceramic total hip arthroplasty is a relatively uncommon phenomenon. It usually does not require treatment in the absence of pain, mechanical symptoms, and/or relentless squeaking. The purpose of this investigation was to report on four patients who presented with hip pain and squeaking due to fractured ceramic liners after ceramic-on-ceramic total hip arthroplasty. METHODS Four patients with painful squeaking after ceramic-on-ceramic total hip arthroplasty were seen at our institution. One patient had a revision for suspected loosening and excessive anteversion of the cup noted on radiographs and magnetic resonance imaging (MRI). The remaining three patients had a revision for audible squeaking with progressive pain. RESULTS Intraoperatively, the ceramic liners of all four patients were fractured. CONCLUSIONS Squeaking after ceramic-on-ceramic total hip arthroplasty rarely is a functional issue. However, painful squeaking without notable trauma may indicate fracture of the ceramic liner. Painful squeaking is difficult to evaluate by conventional imaging. When painful squeaking occurs, exploration via surgical revision is recommended in selected patients, as ceramic liner fractures may go unnoticed on radiographs and/or MRI and thus their actual prevalence may be higher than estimated.

Variability in the Relationship Between the Distal Femoral Mechanical and Anatomical Axes in Patients Undergoing Primary Total Knee Arthroplasty

Currently, an intramedullary (IM) guide is often used for performing the distal femoral resection in total knee arthroplasty (TKA). However, this method assumes that in most patients, the distal femoral mechanical-anatomical angle (FMAA) is 5°. Preoperative, standing, AP hip-to-ankle radiographs were reviewed in 493 patients undergoing primary TKA, and the FMAA was digitally measured. Correlation coefficients relative to several radiographic measurements, along with demographic variables, were performed. A significant number of patients (28.6%) had an FMAA outside the range of 5° ± 2° (range 2.0°-9.6°). The only measurement demonstrating a fair/moderate correlation with the FMAA was the neck-shaft angle (r = -0.55). Using an IM resection guide, without obtaining AP hip-to-ankle radiographs to determine each patients true FMAA, may lead to malalignment of the femoral component.

Radiographic Analysis of a Hand-Held Surgical Navigation System for Tibial Resection in Total Knee Arthroplasty

Tibial intramedullary or extramedullary alignment guides have not been shown to be highly accurate in performing the tibial resection in total knee arthroplasty (TKA). Since May 2010, a total of 42 knees underwent a TKA using a hand-held, accelerometer-based surgical navigation system for performing the tibial resection (KneeAlign; OrthAlign Inc, Aliso Viejo, Calif). Postoperative standing anteroposterior hip-to-ankle and lateral knee-to-ankle radiographs demonstrated that 97.6% of the tibial components were placed within 90° ± 2° to the mechanical axis in the coronal plane, and 96.2% of the components were placed within 3° ± 2° to the mechanical axis in the sagittal plane. The KneeAlign greatly improves the accuracy of tibial component alignment in TKA.