Does It Matter: Total Hip Arthroplasty or Lumbar Spinal Fusion First? Preoperative Sagittal Spinopelvic Measurements Guide Patient-Specific Surgical Strategies in Patients Requiring Both.

BACKGROUND: In patients requiring both total hip arthroplasty (THA) and lumbar spinal fusion (LSF), consideration of preoperative sagittal spinopelvic measurements can aid in the prediction of postfusion compensatory changes in pelvic tilt (PT) and inform adjustments to traditional THA cup anteversion. This study aims to identify relationships between spinopelvic measurements and post-THA hip instability and to determine if procedure order reveals a difference in hip dislocation rate. METHODS: Patients at a single practice site who received both THA and LSF between 2005 and 2015 (292: 158 = LSF prior to THA, 134 = THA prior to LSF) were retrospectively reviewed for incidents of THA instability. Those with complete radiograph series (89) had their sagittal (standing) spinopelvic profiles measured preoperatively, immediately postoperatively, and 3 months, 6 months, 1 year, 1.5 years, and 2 years postoperatively. Measured parameters included lumbar lordosis (LL), pelvic incidence (PI), PT, and sacral slope (SS). RESULTS: No significant differences in dislocation rates between operative order groups were elicited (7/73 LSF first, 4/62 THA first; Z = 0.664, P = .509). Compared to nondislocators, dislocators had lower LL (-10.9) and SS (-7.8), and higher PT (+4.3) and PI-LL (+7.3). Additional risk factors for dislocation included sacral fusion (relative risk [RR] = 3.0) and revision fusion (RR = 2.7) . Predictive power of the model generated through multiple regression to characterize individual profiles of post-LSF PT compensation based on perioperative measurements was most significant at 1 year (R2 = 0.565, F = 0.000456, P = .028) and 2 years (R2 = 0.741, F = 0.031, P = .001) postoperatively. CONCLUSION: In performing THA after LSF, it is theoretically ideal to proceed with THA at a postfusion interval of at least 1 year, beyond which further compensatory PT change is minimal. However, the order of surgical procedure revealed no statistical difference in hip instability rates. In cases characterized by large PI-LL mismatch (larger or less predictable compensation profiles) or large SS or LL loss (considerably atypical muscle recruitment), consideration of full functional anteversion range between sitting and standing positions to account for abnormalities not appreciated with standing radiographic assessment alone may be warranted.

Survivorship of the Modular Femoral Revision Stem.

The geriatric population represents a rapidly growing segment of society with prolonged life expectancies and more active lifestyles. Many of these patients have already undergone primary total hip arthroplasty (THA) and are presenting with aseptic loosening, polyethylene wear, osteolysis, or periprosthetic fractures. Therefore, the demand for hip revision procedures is expected to grow. Currently, there are many modular implant options available for use in complicated revision THA. Early results of modular femoral revision systems are promising for the treatment of the deficient femur in complex revision THA. The objective of this study was to evaluate component survivorship of a modular femoral revision system in revision THA. A retrospective review was conducted using electronic health records of patients who underwent revision THA performed by 1 of 3 surgeon investigators from 2010 through 2014. The authors included all patients who underwent a revision THA using a specific modular femoral revision system. The authors evaluated component survivorship and time to re-revision THA. Fifty-one revision THAs were included. Seven patients required a second revision THA (13.7%; 95% confidence interval, 4%-23%). Mean time to re-revision THA was 4.88±3.9 months. Kaplan-Meier survivorship using re-revision for any reason was 86.3% at 60 months. This study showed excellent component survivorship of the specific modular femoral revision system in revision THA. [Orthopedics. 2019; 42(5):294-298.].

Aspirin Alone Is Not Enough to Prevent Deep Venous Thrombosis After Total Joint Arthroplasty.

Thromboembolic events after total joint arthroplasty are potentially devastating complications. This study evaluated the efficacy of 4 different anticoagulants in preventing deep venous thrombosis and pulmonary embolism after total joint arthroplasty. The demographics and anticoagulant use (warfarin, enoxaparin, and aspirin with and without outpatient mechanical pumps) for patients who underwent primary unilateral total joint arthroplasties performed by a single surgeon from January 2013 to October 2014 were retrospectively reviewed. All patients underwent lower extremity ultrasound at the 3-week postoperative visit. A total of 613 primary unilateral total joint arthroplasties met the study inclusion criteria. There were 288 primary total knee arthroplasties and 325 primary total hip arthroplasties. The patients were 62.2% female, having a mean age of 67.6±10.6 years and a mean body mass index of 30.2±5.9 kg/m2. There were 119 patients in group 1 (aspirin alone), 40 patients in group 2 (aspirin plus pumps), 246 patients in group 3 (warfarin), and 208 patients in group 4 (enoxaparin). The overall 3-week symptomatic and asymptomatic deep venous thrombosis and symptomatic pulmonary embolism rates in the entire cohort were 5.7% and 0.3%, respectively. The venous thromboembolism rate was significantly affected by the anticoagulant of choice (P<.01). Compared with aspirin alone, warfarin decreased the risk of venous thromboembolism (P<.01). Increasing age led to increased risk of venous thromboembolism (P=.05). This study indicated that aspirin chemoprophylaxis alone was not as efficacious as warfarin and enoxaparin in preventing asymptomatic and symptomatic venous thromboembolism found during routine postoperative surveillance with lower extremity ultrasound. Aspirin alone may be inadequate and should be augmented with an outpatient mechanical pump as part of multimodal prophylaxis. [Orthopedics. 2019; 42(1):48-55.].

Alarmingly High Rate of Implant Fractures in One Modular Femoral Stem Design: A Comparison of Two Implants.

BACKGROUND: Reports of implant fracture at the modular junction have been seen in modular neck designs, stem-sleeve modular femoral stems, and diaphyseal engaging bi-body modular stems. To date, however, there has never been a direct comparison between 2 different implant designs from the same modular family. The purpose of this study is to compare the rate of implant failure of 2 such stem-sleeve modular femoral stem designs, the S-ROM and Emperion, to further identify factors which increase the risk of this mode of failure. METHODS: A retrospective, single surgeon, review of our institutional database was performed to compare the 2 groups of patients. RESULTS: A total of 1168 total hip arthroplasty procedures were included in our analysis, 547 (47%) with Emperion and 621 (53%) with S-ROM. Eight (1.5%) fractures in 7 patients occurred in the Emperion group compared to 1 (0.2%) fracture in the S-ROM group (P = .015). CONCLUSION: The precise cause of the stem fractures in our study remains unknown and is likely multifactorial. Given the unexpectedly high rate of catastrophic implant failures in the form of stem fracture at the stem-sleeve junction, we recommend more judicious use of modularity in primary total hip arthroplasty.

Total Knee Arthroplasty in Obesity: In-Hospital Outcomes and National Trends.

BACKGROUND: Both the prevalence of obesity and the utilization rate of total knee arthroplasty are increasing. The rate and proportion of total knee arthroplasty (TKA) performed in the setting of obesity/morbid obesity is increasing significantly over time. METHODS: Using International Classification of Diseases-Ninth Revision codes, we searched the National Hospitals Discharge Survey national database for patients admitted for primary TKA between 2001 and 2010. We then used International Classification of Diseases-Ninth Revision codes for obesity (body mass index = 30-40 kg/m2) and morbid obesity (body mass index, ≥ 40 kg/m2) to select the obese cohorts. RESULTS: We found 29,694 nonobese, 2645 obese, and 1150 morbidly obese patients. There was an increase in each group over time. The rate of obesity/morbid obesity was strongly correlated with time. Obese and morbidly obese patients were more likely to be younger, female, diabetic, and have Medicaid than nonobese patients. Obese and morbidly obese patients had shorter hospital stays and higher home discharge rates than nonobese patients. Obese and morbidly obese patients had lower transfusion rates, shorter hospital stays, and no increase in inpatient wound infection or venous thromboembolic complications than nonobese patients. The Midwest region saw a greater burden of obese TKA patients. CONCLUSION: With the right measures and precautions, satisfactory inhospital outcomes are possible in the obese patient after primary TKA. A limitation of this study is short inhospital stay of the index procedure as complications may present later after discharge.

Perioperative differences in conventional and computer-assisted surgery in bilateral total knee arthroplasty.

Performing bilateral total knee arthroplasties (bTKAs), sequential or staged, is a topic of debate among surgeons. To our knowledge, no studies have compared computer-assisted surgery (CAS) and conventional (CON) procedures for sequential bTKAs. We retrospectively reviewed 124 (62 CAS, 62 CON) sequential bTKAs. CAS-bTKAs required significantly fewer blood transfusions (P = .001) and had significantly better postoperative day 1 (POD-1) hemoglobin (Hgb) levels (P = .001) and POD-2 Hgb levels (P = .01). Mean total blood transfusion units were 0.9 for the CAS group and 1.7 for the CON group. Postoperative range of motion, tourniquet time, length of stay, number of readmissions, and number of reoperations were not significantly different (P > .05). The statistically significant differences between the groups may have resulted from violation of the femoral intramedullary canal during the CON technique.

Finite element analysis of resurfacing depth and obliquity on patella stress and stability in TKA.

Patella resurfacing in total knee arthroplasty (TKA) reduces postoperative complications and revisions; however, the optimal cutting depth and angle that minimize patellar strain and fracture remain unclear. We performed three-dimensional finite element analysis (FEA) of resurfacing cutting depth and obliquity to assess the stresses in each component of the knee joint, and fatigue testing to determine cyclic loading conditions over the expected life span of the implant. Maximum stress on the patella increased as cutting depth increased up to 8mm; peak stresses on the idealized button further increased at 10-mm depth. Medial superior obliquities below 3° showed the lowest stress on the patella and button and the highest fatigue life. An oblique cut of 3° with respect to the inferior end increased patellar stress and reduced fatigue life, making this the least successful approach. Taken together, our FEA supports the use of minimal cutting depths at -3° with respect to the superior end for patellar resurfacing in TKA in order to minimize stresses in the structure and improve TKA durability. Future studies will assess the effect of patella button placement to account for real-world practice variations.

Rotating platform revision total knee arthroplasty.

Although revision total knee arthroplasty (TKA) procedures are successful in relieving pain and restoring function in failed knees, long-term results are inferior to primary procedures. Mobile bearing (MB) revision knees can potentially improve functional performance. Clinical results of 44 MB rotating platform (RP) revision TKAs demonstrated mean knee injury and osteoarthritis outcome score (KOOS) activity of daily living score of 77 2 years postoperatively. Clinical results were put into context through wear testing which demonstrated improved wear performance compared with fixed bearing (FB) revision knees. The RP construct is a good choice for revision TKA because it permits the surgeon to align the tray for fixation, not compromise rotation of the tibial insert, and reduce transmission of shear stresses to the bone, cement and implant interface, which is a known cause of failure.

Mid-term survivorship results for a rotating-platform knee prosthesis.

Interest in mobile-bearing knee prostheses is increasing in the US market. We studied results at 2 to 5 years with a mobile-bearing system that includes a cobalt-chrome tibial tray and femoral component with a polyethylene cruciate-retaining tibial component insert that allows rotation around a central axis and can be used with cruciate-retaining or posterior-stabilized femoral components. The inserts used in this study were cruciate retaining and did not include the posterior-stabilized design. The goal of this study was to demonstrate the function and safety of this prosthesis along with the lack of spinout, which is a major concern in the mobile-bearing knee. Four hundred thirty-five knees constituted the study cohort and underwent survivorship analysis and complication reporting. Routine clinic evaluations included pre- and postoperative radiographs and Knee Society knee and function scores at 6 and 12 weeks and every 2 years. The most recent follow-up data within 2 to 5 years was included for the study along with survey data. Flexion at most recent follow-up averaged 125°. Knee Society score at most recent visit averaged 88 of 100. Knee Society function score averaged 83 of 100. Radiographic results were available for 226 knees, with 97.3% assessed as normal and 6 with these issues: patella stress fracture (3), aseptic tibial loosening (1), patellar osteolysis (1), and patella aseptic loosening (1). In comparison with the fixed-bearing knee equivalent, this mobile-bearing knee demonstrated at least equivalent results in terms of survivorship, function, and patient satisfaction in the short- and mid-term.

Unilateral vs bilateral total knee arthroplasty risk factors increasing morbidity.

Because surgeons are electing to perform simultaneous bilateral total knee arthroplasty (TKA), it is important to identify which patients are at increased risk. We performed a retrospective cohort analysis of 150 patients with unilateral TKA vs 150 patients with simultaneous bilateral TKA. The bilateral group demonstrated a 2.1 times greater mean overall complication rate as well as increased transfusion rates. Patients older than 70 years exhibited significantly higher complication rates. Having a preexisting pulmonary disorder in the bilateral cohort carried nearly a 3-fold risk of complications. Patients with body mass indices greater than 30 displayed a complication rate of 0.97 in the bilateral group as opposed to 0.44 in the control group. Our study demonstrated that age, body mass index, and a preexisting pulmonary disorder resulted in increased complications.

Dislocation of an S-ROM total hip arthroplasty secondary to traumatic femoral stem dissociation from the metaphyseal sleeve.

Modular total hip arthroplasty component dissociation has been reported. We describe a case of recurrent instability secondary to femoral stem dissociation from the proximal metaphyseal sleeve and resultant traumatic retroversion of the neck. Femoral stem revision was necessary for treatment of this rare complication.

Comparison of patient satisfaction with incision cosmesis after standard and minimally invasive total hip arthroplasty.

This study evaluated patient assessments and attitudes regarding incision cosmesis following standard and minimally invasive total hip arthroplasty 1 to 3 years postoperatively. A cosmesis questionnaire designed to elicit a score evaluating scar satisfaction was mailed to patients. Although the difference in total cosmesis score between the standard and minimally invasive groups was not statistically significant, patients with a standard incision had better scores at <1 year. One significant finding was worse responses in the minimal incision patients regarding sinking and curling of scar edges.

Implant sizing of the P.F.C. sigma rotating-platform total knee system.

We studied the P.F.C. Sigma rotating-platform total knee arthroplasties performed during 2004 and 2005 to assess implant size variations in men versus women and size variation in bilateral knees. We subsequently studied commercial femoral radiograph templates to compare mediolateral and anteroposterior dimensions. Sixty-four percent of women more frequently had a tibial tray one size smaller with respect to the femur and 63.5% of men had the same-sized femur and tibia. Bilateral knees were the same size in both sides 97% of the time in women, and 90% in men. The template comparison found that the P.F.C. Sigma rotating-platform femur had a mediolateral dimension that was smaller than many knee replacements commercially available.

Optimizing range of motion in cruciate-retaining mobile-bearing tka: experience with 2000 cases.

We describe experience with 2000 cruciate-retaining Sigma RP total knee arthroplasties performed between September 2000 to January 2006. All procedures were performed with a midvastus arthrotomy, medioposterior release, and posterior condylar clean-out technique. This implant design uses a congruent polyethylene bearing to diminish contact stress while allowing rotation between the polyethylene bearing surface and tibial tray. Of the 2000 knees, 1596 had follow-up data at one year. Seven hundred-twenty-seven had an average flexion of 123 degrees, 692 had an average Knee Society Score of 94, and 672 had an average function score of 86.

Leg length inequality in total hip arthroplasty.

Postoperative leg length inequality after total hip arthroplasty frequently leads to medical liability issues because no standard exists regarding the acceptable disparity. Modular stems allow control of offset, independent sizing of the distal femoral anatomy, as well as proximal medullary sizing. The authors compared the restoration of leg length in two cohort protocols. In the 2001 cohort, tapered stems were exclusively used, giving priority to fit and fill of the medullary canal. In the 2004 cohort, porous-tapered stems, or an S-ROM modular stem (DePuy Orthopaedics Inc., Warsaw, Ind) when needed, were used based on preoperative templating to restore the center of femoral head rotation. Prior to and after surgery, length from center measurements were taken (center of rotation of the femoral head to the top of the lesser trochanter) and the vertical vector to compare the difference in actual leg length. In the 2001 cohort, the mean increase of length from center was 9 mm (7 mm leg length). In the 2004 cohort, 25% of the hips were inappropriate for tapered stems. S-ROMs were used because a tapered stem would lengthen the leg. In the standard offset tapered stem, the mean increase of length from center was 6 mm (4 mm leg length). In the high offset tapered stem, the mean increase of length from center was 7 mm (5 mm leg length). In the S-ROM stem with varying offsets, the mean increase of length from center was 6 mm (4 mm leg length). Only the S-ROM consistently avoids overlengthening in the majority of patients.

Modular femoral component for conversion of previous hip surgery in total hip arthroplasty.

The conversion of previous hip surgery to total hip arthroplasty creates a durable construct that is anatomically accurate. Most femoral components with either cemented or cementless design have a fixed tapered proximal shape. The proximal femoral anatomy is changed due to previous hip surgery for fixation of an intertrochanteric hip fracture, proximal femoral osteotomy, or a fibular allograft for avascular necrosis. The modular S-ROM (DePuy Orthopaedics Inc., Warsaw, Ind) hip stem accommodates these issues and independently prepares the proximal and distal portion of the femur. In preparation and implantation, the S-ROM hip stem creates less hoop stresses on potentially fragile stress risers from screws and thin bone. The S-ROM hip stem also prepares a previously distorted anatomy by milling through cortical bone that can occlude the femoral medullar canals and recreate proper femoral anteversion and reduces the risk of intraoperative or postoperative periprosthetic fracture due to the flexible titanium-slotted stem. The S-ROM femoral stem is recommended for challenging total hip reconstructions.

Posterior-lateral approach to minimal incision total hip arthroplasty.

As surgeons learn to perform minimally invasive hip arthroplasty procedures, the various techniques will evolve and one or two approaches may eventually become the standard. Currently, most of these procedures are reserved for the nonmorbidly obese patients; however, as techniques are perfected and surgeons gain experience, this patient population may eventually be served. Surgeons must present information to patients in a responsible manner and clarify the actual versus perceived advantages of the MITH. It is unfortunate that some patients may abandon an experienced surgeon (who will likely give an excellent long-term clinical outcome) for an inexperienced surgeon who can provide a smaller incision (with long-term benefits thus far unknown). Surgeons must also address the same comorbidities and complications for MITH arthroplasty as with the conventional approaches such as DVT, fat embolism, pain control, and wound healing. Routines for postoperative care and screening for complications must remain within the plan of care for the standard incision and MITH patient.information to patients in a responsible manner and clarify the actual versus perceived advantages of the MITH. It is unfortunate that some patients may abandon an experienced surgeon (who will likely give an excellent long-term clinical outcome) for an inexperienced surgeon who can provide a smaller incision (with long-term benefits thus far unknown). Surgeons must also address the same comorbidities and complications for MITH arthroplasty as with the conventional approaches such as DVT, fat embolism, pain control, and wound healing. Routines for postoperative care and screening for complications must remain within the plan of care for the standard incision and MITH patient.