Incidence of Anterior Knee Pain and Functional Difficulty in a Prospectively Recruited Cohort Following Total Knee Arthroplasty With Selective Patellar Resurfacing.

BACKGROUND: The influence of patellar resurfacing on anterior knee pain, stair climbing, and functional activity outcomes following total knee arthroplasty (TKA) are incompletely understood. This study examined the influence of patellar resurfacing on patient-reported outcome measures (PROMs) relating to anterior knee pain and function. METHODS: The Knee Injury and Osteoarthritis Outcome Score of Joint Replacement (KOOS, JR.) patient PROMs were collected preoperatively and at 12 months follow-up for 950 TKAs performed over 5 years. Indications for patellar resurfacing included Grade IV patello-femoral (PFJ) changes or mechanical PFJ findings during patellar trialing. Patellar resurfacing was performed on 393 (41%) of the 950 TKAs performed. Multivariable binomial logistic regressions were performed, using KOOS, JR. questions assessing pain during stair climbing, standing upright, and function during rising from sitting as surrogates for anterior knee pain. Independent regression models were performed for each of the targeted KOOS, JR. questions, with adjustment for age at surgery, sex, and baseline pain and function. RESULTS: No association was observed between 12-month postoperative anterior knee pain or function with patellar resurfacing (P = .17, .97). Patients who had moderate or greater preoperative pain on stairs had an increased likelihood of postoperative pain and functional difficulty (odds ratio 2.3, P = .013), while males were 42% less likely to report postoperative anterior knee pain (odds ratio 0.58, P = .002). CONCLUSION: Selective patellar resurfacing based on PFJ degeneration and mechanical PFJ symptoms produces similar improvement in PROMs for resurfaced and unresurfaced knees.

What Role Does Patello-Femoral Joint Degeneration Have on Pain and Function After Unicompartmental Knee Arthroplasty? A Prospective Observational Cohort Study.

BACKGROUND: Influences on anterior knee pain, stair climbing limitations, and function such as rising from sitting are poorly understood in unicompartmental knee arthroplasty (UKA). Original indications for UKA excluded patients who had patello-femoral disease, while more recent studies have expanded the indications to include these patients. This study examined the influence of the patello-femoral joint degeneration on patient-reported outcome measures relating to anterior knee pain and function after UKA. METHODS: Between October 2017 and August 2021, Knee Injury and Osteoarthritis Outcome Score of Joint Replacement (KOOS, JR) patient-reported outcome measures were collected preoperatively and at 12 months of follow-up for 678 medial UKAs. Patello-femoral joint status was visually graded intraoperatively. Radiographic or intraoperative medial patellar facet and trochlear patello-femoral arthritis and preoperative anterior knee pain were not considered contraindications for UKA, while grade IV lateral patello-femoral arthritis was considered a contraindication for UKA. Multivariable ordinal logistic regressions were performed, using the KOOS, JR questionnaire assessing pain during stair climbing, standing upright, and function during rising from sitting. Independent regressions were performed for each targeted KOOS, JR question, with adjustments for age at surgery, sex, and baseline pain and function scores. RESULTS: No association was observed between 12-month postoperative anterior knee pain (P = .575) and function (P = .854) with patellar osteoarthritis grading after UKA. When comparing fixed and mobile-bearing UKA designs, no association was observed between bearing type and pain (P = .663) or functional outcomes (P = .758). CONCLUSION: Pain and function improved significantly following medial UKA and was independent of medial patellar and trochlear degenerative status.

Outpatient-Focused Joint Arthroplasty Is the Future: The Midwest Center for Joint Replacement Experience.

BACKGROUND: Perhaps, the most significant developments in joint arthroplasty in the past decade have been in the area of multimodal perioperative management reducing pain, nausea, and length of stay leading to outpatient arthroplasty. METHODS: Over a 2-year period, we performed 1230 arthroplasty cases including partial knee, total hip, total knee, and selected revision cases. RESULTS: Patient satisfaction ranged from 98% to 100% great/good. Ninety-eight percent of patients were discharged the same day. There were no readmissions for pain control and an overall readmission rate of 2%. CONCLUSION: The outpatient program centers on the patient needs, family engagement, essentials of home recovery, preoperative education, efficient surgery, and a surgeon-controlled environment with a highly standardized care. This is a distinct shift in today's health-care environment, which has seen the expansion of regulatory demands; focus on Electronic Health Record, and distractions from real discussions of demonstrated value creation. The future is bright for both ambulatory surgery center and hospital development of successful outpatient joint arthroplasty program for patients and surgeons alike.

Medial Mobile-Bearing Unicompartmental Knee Arthroplasty in Young Patients Aged Less Than or Equal to 50 Years.

BACKGROUND: Contemporary research has shown medial mobile-bearing unicompartmental knee arthroplasty to be an effective treatment in patients younger than 60 years; however, only one other study has specifically investigated unicompartmental arthroplasty outcomes in patients 50 years or younger. The purpose of this study was to determine the clinical outcomes and survivorship of medial mobile-bearing unicompartmental arthroplasty in this younger patient population. METHODS: A retrospective review of patients undergoing primary unicompartmental knee arthroplasty using the Oxford partial knee from 2003 to 2014 in a single practice database was performed. Patients were included in the study if they were 50 years of age or younger with a primary diagnosis of anteromedial osteoarthritis and minimum clinical follow-up of 2 years. Patient clinical outcomes, function, and need for revision surgery were assessed. RESULTS: The study included 340 knees. Average patient age was 46.5 years, and the mean follow-up was 6.1 years. Patients demonstrated significant improvements (P < .05) in range of motion (114.5 v 116.9), University of California Los Angeles activity score (4.4 vs 5.6), Knee Society clinical (37.3 vs 86.5) and functional scores (58.8 v 79.8). Overall, 20 patients required reoperation, and the predicted survival rate was 96% at 6 years and 86% at 10 years. Aseptic loosening occurred in 7 patients at an average of 5.6 years postoperatively, while 4 patients required conversion to total knee arthroplasty because of arthritic progression at a mean time of 6.6 years. There were no revision procedures required due to polyethylene liner wear or breakage. CONCLUSION: Medial mobile-bearing unicompartmental arthroplasty should be considered as a treatment option in patients younger than 50 years of age suffering from anteromedial osteoarthritis of the knee.

Characterization of Femoral Component Initial Stability and Cortical Strain in a Reduced Stem-Length Design.

BACKGROUND: Short-stemmed femoral components facilitate reduced exposure surgical techniques while preserving native bone. A clinically successful stem should ideally reduce risk for stress shielding while maintaining adequate primary stability for biological fixation. We asked (1) how stem-length changes cortical strain distribution in the proximal femur in a fit-and-fill geometry and (2) if short-stemmed components exhibit primary stability on par with clinically successful designs. METHODS: Cortical strain was assessed via digital image correlation in composite femurs implanted with long, medium, and short metaphyseal fit-and-fill stem designs in a single-leg stance loading model. Strain was compared to a loaded, unimplanted femur. Bone-implant micromotion was then compared with reduced lateral shoulder short stem and short tapered-wedge designs in cyclic axial and torsional testing. RESULTS: Femurs implanted with short-stemmed components exhibited cortical strain response most closely matching that of the intact femur model, theoretically reducing the potential for proximal stress shielding. In micromotion testing, no difference in primary stability was observed as a function of reduced stem length within the same component design. CONCLUSION: Our findings demonstrate that within this fit-and-fill stem design, reduction in stem length improved proximal cortical strain distribution and maintained axial and torsional stability on par with other stem designs in a composite femur model. Short-stemmed implants may accommodate less invasive surgical techniques while facilitating more physiological femoral loading without sacrificing primary implant stability.

A Finite-Element Study of Metal Backing and Tibial Resection Depth in a Composite Tibia Following Total Knee Arthroplasty.

Prosthetic alignment, patient characteristics, and implant design are all factors in long-term survival of total knee arthroplasty (TKA), yet the level at which each of these factors contribute to implant loosening has not been fully described. Prior clinical and biomechanical studies have indicated tibial overload as a cause of early TKA revision. The purpose of this study was to determine the relationship between tibial component design and bone resection on tibial loading. Finite-element analysis (FEA) was performed after simulated implantation of metal backed (MB) and all-polyethylene (AP) TKA components in 5 and 15 mm of tibial resection into a validated intact tibia model. Proximal tibial strains significantly increased between 13% and 199% when implanted with AP components (p < 0.05). Strain significantly increased between 12% and 209% in the posterior tibial compartment with increased bone resection (p < 0.05). This study indicates elevated strains in AP implanted tibias across the entirety of the proximal tibial cortex, as well as a posterior shift in tibial loading in instances of increased resection depth. These results are consistent with trends observed in prior biomechanical studies and may associate the documented device history of tibial collapse in AP components with increased bone strain and overload beneath the prosthesis.

Outpatient Arthroplasty is Here Now.

Substantial advances have been made in arthroplasty to minimize surgical trauma and maximize perioperative pain control, which has enabled patients to regain mobility within hours of surgical intervention and be safely discharged to home the same day. Surgeons should understand the indications and contraindications for the safe performance of outpatient arthroplasty in a hospital and ambulatory surgical center setting as well as know how to optimize, medically manage, prepare, and rehabilitate patients. To undertake outpatient arthroplasty, surgeons must be knowledgeable in multimodal anesthesia techniques, effective venous thromboembolism prophylaxis, blood management, and wound management. In addition, surgeons must learn the subtle nuances of specialized surgical techniques that lend themselves to outpatient arthroplasty, including partial knee, muscle-sparing total hip, less invasive total knee, and total shoulder techniques.

Residual Symptoms and Function in Young, Active Hip Arthroplasty Patients: Comparable to Normative Controls?

BACKGROUND: Whether patient-reported symptoms and function after total hip and surface replacement arthroplasty in young, active patients compare favorably to those without known hip pathology has not been investigated. METHODS: A retrospective, multicenter study was designed in which 5 centers contributed patients aged <60 years with a presymptomatic University of California at Los Angeles score ≥6 undergoing hip arthroplasty. Data were collected by an independent, third-party survey center that administered a questionnaire assessing patient satisfaction and function. A "control" population with no prior hip interventions or hip pathology limiting their activity, that met the age and activity criteria, was identified for comparison using multivariate regression analyses. RESULTS: Eight-hundred six hip arthroplasties (682 total hip arthroplasty, 124 surface replacement arthroplasty) and 158 controls were included. A greater percentage of hip arthroplasty patients were male and aged >50 years which was controlled during multivariate regression analyses. Control patients reported the presence of a limp (15%), stiffness (11%), and pain in the hip (8%), but to a lesser degree than hip arthroplasty patients. Control patients were less likely to report pain in the hip (odds ratio [OR] = 0.4, 95% confidence interval [CI] = 0.2-0.7, P = .006), stiffness in the hip (OR = 0.5, 95% CI = 0.3-0.8, P = .02), and a limp (OR = 0.5, 95% CI = 0.3-0.8, P < .001) vs patients undergoing hip arthroplasty. CONCLUSION: When interviewed by an independent third party, a substantial portion of control patients did note the presence of hip symptoms, but to a lesser degree than young, active patients undergoing hip arthroplasty.

Residual Symptoms and Function After Unicompartmental and Total Knee Arthroplasty: Comparable to Normative Controls?

BACKGROUND: Whether patient-reported symptoms and function after total knee arthroplasty (TKA) and medial unicompartmental knee arthroplasty (UKA) compare favorably to similar individuals without a diagnosis of knee pathology has not been investigated. METHODS: A retrospective, multicenter study was designed in which 4 centers contributed patients between ages 18 and 80 years undergoing knee arthroplasty. Data were collected by an independent, third-party survey center that administered a questionnaire assessing patient satisfaction and function. The survey center identified a "control" population of the same age range using a "random digit dial call method" with no prior knee interventions or major problems with their knees limiting their activity. Comparisons were performed using multivariate logistic regression analyses accounting for differences in demographic variables among the 3 cohorts. RESULTS: Overall, 1456 TKAs, 476UKAs, and 409 controls were included for analysis. Controls reported a surprisingly high incidence of pain (30%), a limp (26%), stiffness (22%), and noise (21%) in their knee. However, the likelihood of reported noise (odds ratio [OR], 1.3), swelling (OR, 1.4), stiffness (OR, 1.8), and difficulty getting in and out of a chair (OR, 2.5) was increased after TKA vs controls (P < .001-.03). The likelihood of swelling (OR, 1.8), stiffness (OR, 1.5), and difficulty getting in and out of a chair (OR, 1.7) was increased after UKA vs controls (P = .002-.005). CONCLUSION: When interviewed by an independent, third party, a substantial percentage of control patients reported the presence of knee symptoms, but to a lesser degree than patients after a knee arthroplasty.

Twenty-year followup of an uncemented stem in primary THA.

BACKGROUND: Uncemented stems have been used in THA for well over two decades, but there are relatively few studies reporting on the results after 20 years. QUESTIONS/PURPOSES: The purpose of this study was to evaluate at a minimum followup of 20 years (1) hip scores; (2) radiographic findings, including stem fixation and osteolysis; (3) reoperations; and (4) survivorship free from aseptic loosening in a group of patients who underwent primary THA using a proximally porous-coated, plasma-sprayed, straight-stemmed, titanium-alloy femoral component. METHODS: Between 1987 and 1993, we performed 1517 primary THAs, of which 447 were cementless, and 157 used the implant under study here (representing 10% of the THAs during the period in question). General indications for the use of the study stem included (1) younger age with relatively stronger bone (average age 55 years in this study); (2) patients not involved in another study protocol (as were the 278 other cementless hips implanted during this time); and (3) patients who, at the surgeon's discretion, would be compliant with protected weightbearing. Of those, 111 were available for followup at a minimum of 20 years (mean, 20 years), whereas 36 had died and nine (6%) were lost to followup or declined participation. The primary diagnosis was osteoarthritis in 77 hips (69%). The mean age at operation was 55 years. The clinical result was evaluated on the basis of the Harris hip score. Radiographic analysis was performed at each followup visit for distal cortical hypertrophy, spot welds, radiolucencies, stem subsidence, varus or valgus shift, osteolysis, and femoral component loosening. Kaplan-Meier analysis was performed to evaluate the survival of the femoral component. RESULTS: The mean Harris hip score improved from 46 points to 87 points (of a possible 100 points) at the most recent followup. All hips had evidence of proximal femoral remodeling consistent with osseous ingrowth. Femoral osteolyis was seen in 22 hips (20%). One stem was revised as a result of a periprosthetic fracture. No femoral component had evidence of loosening, and none was revised. Thirty-three acetabular components (30%) were revised. CONCLUSIONS: This femoral component provided durable long-term fixation for over two decades after THA. The porous stem geometry is still in use today and will continue to be studied into the third decade of use. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Ensuring a Winner: The ABCs of Primary Total Knee Arthroplasty.

Total knee arthroplasty is a common and immensely successful surgical procedure that reliably relieves pain and improves function. However, early revision rates and patient dissatisfaction are high suggesting that there is need for improvement through careful patient selection and education as well as attention to surgical technique. After ensuring that a patient is an appropriate candidate for the procedure, patient education is critical to ensure appropriate expectations. Careful preoperative planning and achieving appropriate alignment, sizing, and ligament balance are critical for optimal knee function. Careful attention to the cement technique is important for long-term implant fixation. With appropriate patient selection and careful surgical techniques, optimal patient outcomes will be achieved.

Use of screws and cement in revision TKA with primary or revision specific prosthesis with up to 17 years followup.

The purpose of this study was to investigate the use for screws and cement, and primary and revision specific prosthesis for revision TKA. Between July 1989 and February 2010, 839 consecutive revision TKAs were performed, with 609 knees meeting inclusion criteria. At 17 years followup, Kaplan-Meier survivorship was 0.9859 for revision specific prosthesis with screws and cement, 0.9848 for revision prosthesis with no screws, 0.9118 for primary prosthesis with screws, and 0.9424 for primary prosthesis with no screws. Revision TKAs using screws had greater defects (P<.0001). Use of revision prosthesis along with screws and cement to correct largely defective revision TKAs is highly recommended.

The impact of total joint arthroplasty on sexual function in young, active patients.

There is limited information regarding sexual function following total hip (THA) and knee arthroplasty (TKA). A multicenter study of 806 THA, 542 TKA, and 181 control patients less than 60 years of age was conducted using an independent survey center to question subjects about their sexual function. Only 1.3% of THA and 1.6% of TKA patients stated they were not sexually active due to their operation. No significant differences were noted in sexual function based on the bearing surface, femoral head size, or use of surface replacement arthroplasty in the hip cohort. Multivariate analysis revealed no difference in the percentage of patients sexually active following a THA or TKA (OR 1.19, P=0.38). Most young active patients return to sexual activity after hip and knee arthroplasty.

Consensus Statement on Indications and Contraindications for Medial Unicompartmental Knee Arthroplasty.

Previous work, now nearly 30 years dated, is frequently cited as the "gold standard" for the indications and contraindications for medial unicompartmental knee arthroplasty (UKA). The purpose of this article is to review current literature on the indications and contraindications to UKA and develop a consensus statement based on those data. Six surgeons with a combined experience of performing more than 8,000 partial knee arthroplasties were surveyed. Surgeons then participated in a discussion, emerging proposal, collaborative modification, and final consensus phase. The final consensus on primary indications and contraindications is presented. Notably, the authors provide consensus on previous contraindications, which are no longer considered to be contraindications. The authors provide an updated and concise review of the current indications and contraindications for medial UKA using scientifically based consensus-building methodology.

Use of screws and cement in primary TKA with up to 20 years follow-up.

The purpose of this study was to investigate screws and cement for large tibial bone defects during primary TKA. Of 14,686 consecutive primary TKAs performed between December 1988 and February 2010, 256 received screws and cement for tibial defects. Cox regression was used for the analysis. 20-year survival probability was 0.9897 (screws) and 0.9339 (no screws) (P = .4225 log-rank). Tibial bone condition was significantly worse in knees receiving screws (P < .0001) with 73.0% having defects in the screws group and 3.4% (P < .0001) for non-screws. Radiolucency appeared in 13.7% (screws) and 6.4% (no screws) postoperatively. Screws were $137 each, wedges $910 to $2240. Knees with tibial defects and screws performed similarly if not better than knees without defects at substantially lower cost than alternatives.

The effect of rotating platform TKA on strain distribution and torque transmission on the proximal tibia.

Limited experimental data exist comparing the mechanical response of the tibial cortex between fixed and rotating platform (RP) total knee arthroplasty (TKA), particularly in the revision setting. We asked if RP-TKA significantly affects tibiofemoral torque and cortical stain response in both the primary and revision settings. Fixed and RP tibial trays were implanted into analogue tibias and biomechanically tested under axial and torsional loading. Torque and strain response were analyzed using digital image correlation. Fixed bearing designs exhibited 13.8 times greater torque (P<0.01), and 69% (P<0.01) higher cortical strain than RP designs. Strain response was similar in the primary and revision cohorts. The decrease in torque transfer could act as a safeguard to reduce stress, micromotion and torsional fatigue in scenario of poor bone stock.

Acetabular cup design influences deformational response in total hip arthroplasty.

BACKGROUND: Press-fit acetabular components are susceptible to deformation in an underreamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction and micromotion. Specifically, however, it remains unclear how cup diameter, design, and time from implantation affect shell deformation. QUESTIONS/PURPOSES: We asked whether (1) changes in component geometry and material altered maximum shell deformation and (2) time-dependent deformational relaxation processes occurred. METHODS: Diametral deformation was quantified after press-fit implantation of metal shells into a previously validated polyurethane model. Experimental groups (n = 6-8) consisted of 48-, 54-, 60-, and 66-mm MOM cups of 6-mm wall thickness, 58-mm cups of 10-mm wall thickness, and CoCrMo and Ti6Al4V 58-mm modular cups. RESULTS: Greater cup diameter, thinner wall construction, and Ti6Al4V modular designs generated conditions for maximum shell deformation ranging from 0.047 to 0.267 mm. Relaxation (18%-32%) was observed 120 hours postimplantation in thin-walled and modular designs. CONCLUSIONS: Our findings demonstrate a reduction of shell deformation over time and suggest, under physiologic loading, early component deformation varies with design. CLINICAL RELEVANCE: Component deformation should be a design consideration regardless of bearing surface. Designs neglecting to adequately address deformational changes in vivo could be susceptible to diminished cup survival, increased wear, and premature revision.

Do young, active patients perceive advantages after surface replacement compared to cementless total hip arthroplasty?

BACKGROUND: Potential advantages suggested but not confirmed for surface replacement arthroplasty (SRA) over THA include lower frequency of limp, less thigh pain, less limb length discrepancy, and higher activity. QUESTIONS/PURPOSES: We therefore determined whether patients having SRA had a limp, thigh pain, or limb length discrepancy less frequently or had activity levels higher than patients having THA. METHODS: In a multicenter study, we surveyed 806 patients aged 18 to 60 years with a premorbid UCLA activity score of 6 or more who underwent hip arthroplasty for noninflammatory arthritis at one of five orthopaedic centers. Patients had either a cementless THA with an advanced bearing surface (n = 682) or an SRA (n = 124). The patients were demographically comparable. Specific telephone survey instruments were designed to assess limp, thigh pain, perception of limb length, and activity levels. Minimum followup was 1 year (mean, 2.3 years; range, 1.1-3.9 years). RESULTS: When controlled for age, sex, and premorbid activity level, patients with SRA had a higher incidence of complete absence of any limp, lower incidence of thigh pain, lower incidence of perception of limb length discrepancy, greater ability to walk continuously for more than 60 minutes, higher percentage of patients who ran after surgery, greater distance run, and higher percentage of patients who returned to their most favored recreational activity. CONCLUSIONS: When interviewed by an independent third party, patients with SRA reported higher levels of function with fewer symptoms and less perception of limb length discrepancy compared to a similar cohort of young, active patients with THA.

Acetabular cup stiffness and implant orientation change acetabular loading patterns.

Acetabular cup orientation has been shown to influence dislocation, impingement, edge loading, contact stress, and polyethylene wear in total hip arthroplasty. Acetabular implant stiffness has been suggested as a factor in pelvic stress shielding and osseous integration. This study was designed to examine the combined effects of acetabular cup orientation and stiffness and on pelvic osseous loading. Four implant designs of varying stiffness were implanted into a composite hemipelvis in 35° or 50° of abduction. Specimens were dynamically loaded to simulate gait and pelvic strains were quantified with a grid of rosette strain gages and digital image correlation techniques. Changes in the joint reaction force orientation significantly altered mean acetabular bone strain values up to 67%. Increased cup abduction resulted in a 12% increase along the medial acetabular wall and an 18% decrease in strain in inferior lateral regions. Imbalanced loading distributions were observed with the stiffer components, resulting in higher, more variable, and localized surface strains. This study illustrates the effects of cup stiffness, gait, and implant orientation on loading distributions across the implanted pelvis.

High initial stability in porous titanium acetabular cups: a biomechanical study.

Initial stability with limited micromotion in uncemented total hip arthroplasty acetabular components is essential for bony attachment and long-term biomechanical fixation. This study compared porous titanium fixation surfaces to clinically established, plasma-sprayed designs in terms of interface stability and required seating force. Porous plasma-sprayed modular and metal-on-metal (MOM) cups were compared to a modular, porous titanium designs. Cups were implanted into polyurethane blocks with1-mm interference fit and subsequently edge loaded to failure. Porous titanium cups exhibited 23% to 65% improvement in initial stability when compared to plasma-sprayed cup designs (P=.01): a clinically significant increase, based on experience and prior literature. The results of this study indicate increased interface stability in porous titanium-coated cups without significantly increasing the necessary force and energy required for full seating.