Clinical and Biomechanical Evaluation of Mid-Level Constrained and Posterior-Stabilized Polyethylene Inserts in Primary Total Knee Arthroplasty: An Analysis of 12,674 Cases

BACKGROUND

Mid-level constraint polyethylene designs provide additional stability in total knee arthroplasty (TKA). The purposes of this study were to (1) compare the survivorship and reason for revision between mid-level inserts and posterior-stabilized (PS) used in primary TKA and (2) evaluate the biomechanical constraint characteristics of mid-level inserts.

METHODS

We reviewed all cases of primary TKA performed at our institution from 2016 to 2019 using either PS or mid-level constrained inserts from 1 of 6 manufacturers. Data elements included patient demographics, implants, reasons for revision, and whether a manipulation under anesthesia was performed. We performed finite element analyses to quantify the varus/valgus and axial-rotation constraint of each mid-level constrained insert. A one-to-one propensity score matching was conducted between the patients with mid-level and PS inserts to match for variables, which yielded 2 cohorts of 3,479 patients.

RESULTS

For 9,163 PS and 3,511 mid-level TKAs, survivorship free from all-cause revision was estimated up to 5 years and was lower for mid-level than PS inserts (92.7 versus 94.1%, respectively, P = .004). When comparing each company's mid-level insert to the same manufacturer's PS insert, we found no differences in all-cause revision rates (P ≥ .91) or revisions for mechanical problems (P ≥ .97). Using propensity score matching between mid-level and PS groups, no significant differences were found in rates of manipulation under anesthesia (P = .72), all-cause revision (P = .12), revision for aseptic loosening (P = .07), and revision for instability (P = .45). Finite element modeling demonstrated a range in varus/valgus constraint from ±1.1 to >5°, and a range in axial-rotation constraint from ±1.5 to ±11.5° among mid-level inserts.

CONCLUSIONS

Despite wide biomechanical variations in varus/valgus and axial-rotation constraint, we found minimal differences in early survivorship rates between PS and mid-level constrained knees.

Impact of Selective Posterior Cruciate Ligament Fiber Release on Femoral Rollback in Cruciate-Retaining Total Knee Arthroplasty: A Computational Study

BACKGROUND

Partial or total release of the posterior cruciate ligament (PCL) is often performed intraoperatively in cruciate-retaining total knee arthroplasty (CR-TKA) to alleviate excessive femoral rollback. However, the effect of the release of selected fibers of the PCL on femoral rollback in CR-TKA is not well understood. Therefore, we used a computational model to quantify the effect of selective PCL fiber releases on femoral rollback in CR-TKA.

METHODS

Computational models of 9 cadaveric knees (age: 63 years, range 47 to 79) were virtually implanted with a CR-TKA. Passive flexion was simulated with the PCL retained and after serially releasing each individual fiber of the PCL, starting with the one located most anteriorly and laterally on the femoral notch and finishing with the one located most posteriorly on the medial femoral condyle. The experiment was repeated after releasing only the central PCL fiber. The femoral rollback of each condyle was defined as the anterior-posterior distance between tibiofemoral contact points at 0° and 90° of flexion.

RESULTS

Release of the central PCL fiber in combination with the anterolateral (AL) fibers, reduced femoral rollback a median of 1.5 [0.8, 2.1] mm (P = .01) medially and by 2.0 [1.2, 2.5] mm (P = .04) laterally. Releasing the central fiber alone reduced the rollback by 0.7 [0.4, 1.1] mm (P < .01) medially and by 1.0 [0.5, 1.1] mm (P < .01) laterally, accounting for 47 and 50% of the reduction when released in combination with the AL fibers.

CONCLUSIONS

Releasing the central fibers of the PCL had the largest impact on reducing femoral rollback, either alone or in combination with the release of the entire AL bundle. Thus, our findings provide clinical guidance regarding the regions of the PCL that surgeons should target to reduce femoral rollback in CR-TKA.

Is Tibial Bone Mineral Density Related to Sex, Age, Preoperative Alignment, or Fixation Method in Primary Total Knee Arthroplasty?

BACKGROUND

Cementless total knee arthroplasty (TKA) has regained interest for its potential for long-term biologic fixation. The density of the bone is related to its ability to resist static and cyclic loading and can affect long-term implant fixation; however, little is known about the density distribution of periarticular bone in TKA patients. Thus, we sought to characterize the bone mineral density (BMD) of the proximal tibia in TKA patients.

METHODS

We included 42 women and 50 men (mean age 63 years, range: 50 to 87; mean body mass index 31.6, range: 20.5 to 49.1) who underwent robotic-assisted TKA and had preoperative computed tomography scans with a BMD calibration phantom. Using the robotic surgical plan, we computed the BMD distribution at 1 mm-spaced cross-sections parallel to the tibial cut from 2 mm above the cut to 10 mm below. The BMD was analyzed with respect to patient sex, age, preoperative alignment, and type of fixation.

RESULTS

The BMD decreased from proximal to distal. The greatest changes occurred within ± 2 mm of the tibial cut. Age did not affect BMD for men; however, women between 60 and 70 years had higher BMD than women ≥ 70 years for the total cut (P = .03) and the medial half of the cut (P = .03). Cemented implants were used in 1 86-year-old man and 18 women (seven < 60 years, seven 60 to 70 years, and four ≥ 70 year old). We found only BMD differences between cemented or cementless fixation for women < 60 years.

CONCLUSIONS

To our knowledge, this is the first study to characterize the preoperative BMD distribution in TKA patients relative to the intraoperative tibial cut. Our results indicate that while sex and age may be useful surrogates of BMD, the clinically relevant thresholds for cementless knees remain unclear, offering an area for future studies.

A novel computational workflow to holistically assess total knee arthroplasty biomechanics identifies subject-specific effects of joint mechanics on implant fixation

Computational studies of total knee arthroplasty (TKA) often focus on either joint mechanics (kinematics and forces) or implant fixation mechanics. However, such disconnect between joint and fixation mechanics hinders our understanding of overall TKA biomechanical function by preventing identification of key relationships between these two levels of TKA mechanics. We developed a computational workflow to holistically assess TKA biomechanics by integrating musculoskeletal and finite element (FE) models. For our initial study using the workflow, we investigated how tibiofemoral contact mechanics affected the risk of failure due to debonding at the implant-cement interface using the four available subjects from the Grand Challenge Competitions to Predict In Vivo Knee Loads. We used a musculoskeletal model with a 12 degrees-of-freedom knee joint to simulate the stance phase of gait for each subject. The computed tibiofemoral joint forces at each node in contact were direct inputs to FE simulations of the same subjects. We found that the peak risk of failure did not coincide with the peak joint forces or the extreme tibiofemoral contact positions. Moreover, despite the consistency of joint forces across subjects, we observed important variability in the profile of the risk of failure during gait. Thus, by a combined evaluation of the joint and implant fixation mechanics of TKA, we could identify subject-specific effects of joint kinematics and forces on implant fixation that would otherwise have gone unnoticed. We intend to apply our workflow to evaluate the impact of implant alignment and design on TKA biomechanics.

To Stage or Not to Stage? Comparison of Patient-Reported Outcomes, Complications, and Discharge Disposition After Staged and Simultaneous Bilateral Posterior Total Hip Arthroplasty

BACKGROUND

Patients who have bilateral hip arthritis can be treated with bilateral total hip arthroplasty (bTHA) in either a staged or simultaneous fashion. The goal of this study was to determine whether staged and simultaneous posterior bTHA patients differ in regard to (1) patient-reported outcome measures, (2) 90-day complication rates, and (3) discharge dispositions and cumulative lengths of stay.

METHODS

Patients who (1) underwent simultaneous bTHA or staged bTHA (within 12 months) using the posterior approach, and (2) completed preoperative and 1-year postoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement surveys were included in the study. A total of 266 patients (87 simultaneous bTHA and 179 staged bTHA) were included. Chart review was performed to collect patient-level variables, postoperative complications, discharge dispositions, and lengths of stay.

RESULTS

Staged bTHA patients had higher Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement, Lower Extremity Activity Scale, and Veterans RAND 12-Item Health Survey physical component scores compared to simultaneous bTHA patients at 6 weeks after surgery (P = .019, .006, and .008, respectively), but these differences did not meet the minimal clinically important difference threshold for any questionnaire. Simultaneous bTHA was associated with higher rate of periprosthetic fractures (P = .034) and discharge to a location other than home (P < .001).

CONCLUSIONS

There were statistically significant, but likely not clinically meaningful differences in patient-reported outcomes for staged and simultaneous bTHA patients at 6 weeks after surgery. Surgeons should be aware of the higher periprosthetic fracture risk and greater likelihood of discharge to a rehabilitation facility associated with simultaneous bTHA. Further research should aim to understand which patients may benefit most from simultaneous bTHA.

Posterior-stabilized versus mid-level constraint polyethylene components in total knee arthroplasty

Aims

Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model.

Methods

We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition.

Results

Mid-level inserts reduced varus angulations compared to PS inserts by a median of 0.4°, 0.9°, and 1.5° at 0°, 30°, and 90° of flexion, respectively, and reduced valgus angulations by a median of 0.3°, 1.0°, and 1.2° (p ≤ 0.027 for all comparisons). Mid-level inserts reduced net IE rotations by a median of 5.6°, 14.7°, and 17.5° at 0°, 30°, and 90°, respectively (p = 0.012). Mid-level inserts reduced anterior tibial translation only at 90° of flexion by a median of 3.0 millimetres (p = 0.036). With an applied varus moment, the mid-level insert decreased LCL force compared to the PS insert at all three flexion angles that were tested (p ≤ 0.036). In contrast, with a valgus moment the mid-level insert did not reduce MCL force. With an applied internal rotation moment, the mid-level insert decreased LCL force at 30° and 90° by a median of 25.7 N and 31.7 N, respectively (p = 0.017 and p = 0.012). With an external rotation moment, the mid-level insert decreased MCL force at 30° and 90° by a median of 45.7 N and 20.0 N, respectively (p ≤ 0.017 for all comparisons). With an applied anterior load, MCL and LCL forces showed no differences between the two inserts at 30° and 90° of flexion.

Conclusion

The mid-level insert used in this study decreased coronal and axial plane laxities compared to the PS insert, but its stabilizing benefit in the sagittal plane was limited. Both mid-level and PS inserts depended on the MCL to resist anterior loads during a simulated clinical exam of anterior laxity.

Clinical and Biomechanical Characteristics of Posterior-Stabilized Polyethylene Post Fractures in Total Knee Arthroplasty: A Retrieval Analysis

BACKGROUND

Fractures of the polyethylene post are a rare but known complication after posterior-stabilized (PS) total knee arthroplasty (TKA). We evaluated the polyethylene and patient characteristics for 33 primary PS polyethylene components that were revised with fractured posts.

METHODS

We identified 33 PS inserts revised between 2015 and 2022. Patient characteristics collected included age at index TKA, sex, body mass index, length of implantation (LOI), and patient-reported details on events surrounding the post fracture. Implant characteristics recorded were manufacturer, cross-linking properties (highly cross-linked polyethylene [XLPE] versus ultra-high molecular weight polyethylene [UHMWPE]), wear characteristics based on subjective scoring of the articular surfaces and scanning electron microscopy (SEM) of fracture surfaces. Mean age at index surgery was 55 years (range, 35 to 69), mean body mass index was 29.5 (range, 18.5 to 37.2), and mean LOI was 10.0 (range, 4 to 26).

RESULTS

Total surface damage scores were significantly higher in the UHMWPE group versus the XLPE group (57.3 versus 44.2, P = .003). SEM demonstrated fracture initiation at the posterior edge of the post in 10 of 13 cases. UHMWPE fracture surfaces posts had more tufted, irregularly clamshell features, while XLPE posts had more precise clamshell marking and a diamond pattern in the region of acute, final fracture.

CONCLUSION

Characteristics of PS post fracture differed between XLPE and UHMWPE implants, with fractures occurring in the XLPE with less generalized surface damage, after a shorter LOI, and with SEM evaluation indicative of a more brittle fracture pattern.

Defining a successful total knee arthroplasty: a systematic review of metrics of clinically important changes

BACKGROUND

Despite the increasing use of patient-reported outcome measures (PROMs), the methodology used to evaluate clinically significant postoperative outcomes after total knee arthroplasty (TKA) is variable. The review aimed to survey studies with identified PROM-based metrics of clinical efficacy and the assessment procedures after TKA.

METHODS

The MEDLINE database was queried from 2008-2020. Inclusion criteria were: full texts, English language, primary TKA with minimum one-year follow-up, use of metrics for assessing clinical outcomes with PROMs, and primary derivations of metrics. The following PROM-based metrics were identified: minimal clinically important difference (MCID), minimum detectable change (MDC), patient acceptable symptom state (PASS), and substantial clinical benefit (SCB). Study design, PROM value data, and methods of derivation for metrics were recorded.

RESULTS

We identified 18 studies (including 46,173 patients) that met the inclusion criteria. Across these studies, 10 different PROMs were employed, and MCID was derived in 15 studies (83%). The MCID was calculated using anchor-based techniques in nine studies (50%) and distribution techniques in eight studies (44%). PASS values were presented in two studies (11%) and SCB in one study (6%) using an anchor-based method; MDC was derived in four studies (22%) using the distribution method.

CONCLUSION

There is variability in the TKA literature with respect to the definition and derivation of measurements of clinically significant outcomes. Standardization of these values may have implications for optimal case selection and PROM-based quality measurement, ultimately improving patient satisfaction and outcomes.

Undersizing the Tibial Baseplate in Cementless Total Knee Arthroplasty has Only a Small Impact on Bone-Implant Interaction: A Finite Element Biomechanical Study

BACKGROUND

The tibial component in total knee arthroplasty (TKA) is often chosen to maximize coverage of the tibial cut, which can result in excessive internal rotation of the component. Optimal rotational alignment may require a smaller baseplate with suboptimal coverage that could threaten fixation. We asked: "does undersizing the tibial component of a cementless TKA to gain external rotation increase the risk of bone failure?"

METHODS

We developed computational finite element (FE) analysis models from the computed tomography (CT) scans of 12 patients scheduled for primary TKA. The models were implanted with a cementless tibial baseplate that maximized coverage and one or two sizes smaller and externally rotated by 5°. We calculated the risk of bone collapse under loads representative of stair ascent.

RESULTS

Undersizing the implant increased the area at risk of collapse for eight patients. However, the area at risk of collapse for the undersized implant (range, 5.2%-16.4%) was no different (P = .24) to the optimally sized implant (range, 4.5%-17.9%). The bone at risk of collapse was concentrated along the posterior edge of the implant. The area at risk of collapse was not proportional to implant size, and for four subjects undersizing the implant actually decreased the area at risk of collapse.

CONCLUSION

While implants should maximize coverage of the tibial cut and seek support on dense bone, undersizing the tibial component to gain external rotation had minimal impact on the load transfer to the underlying bone. This FE analysis model of a cementless tibial baseplate may require further validation and additional studies to investigate the long-term biomechanical effects of undersizing the tibial baseplate. In conclusion, while surgeons should strive to use the appropriate tibial baseplate for each patient, our model identified only minor biomechanical consequences of undersizing the implant for the immediate postoperative bone-implant interaction and implant subsidence.

Mid-Flexion Instability After Total Knee Arthroplasty: Diagnosis, Implant Design, and Outcomes

Mid-flexion instability (MFI) in total knee arthroplasty refers to a distinct clinical entity where the knee is stable at full extension and 90° of flexion, but unstable somewhere between these 2 points. The presentation of MFI is often vague, and studies defining objective clinical or intraoperative measurements are limited. In this review, we aim to properly define the condition, describe diagnostic criteria and risk factors contributing to MFI, review current implant design, and present outcomes of revision surgery performed for MFI. [Orthopedics. 2023;46(1):e13-e19.].

Tumors Constitute a Majority of Total Knee Arthroplasty in Patients <21 Years Old: A United States Nationwide Analysis

BACKGROUND

Total knee arthroplasty (TKA) is rarely performed in patients under 21 years old, but the frequency of utilization of TKA in this population in the United States is not known. The purpose of this study was to evaluate trends in the use of TKA in patients <21 in the United States. Additionally, we aimed to determine the characteristics of these patients and the hospitals in which this procedure is performed.

METHODS

We retrospectively reviewed the Kids' Inpatient Database, a national weighted sample of all inpatient hospital admissions in the United States in patients <21 years of age. We used International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes to identify patients undergoing TKA from 2000 to 2019 and determine a primary diagnosis. Descriptive statistics were calculated using the appropriate sample weights.

RESULTS

The total weighted number of TKAs performed in patients <21 years from 2000 to 2019 was 1,535. There were 70.9% of TKAs performed for a primary diagnosis of tumor, and the use of TKA for malignant tumors has increased. In contrast, the use of TKA for inflammatory arthritis/juvenile idiopathic arthritis decreased significantly over the study period. The majority of TKAs were performed in urban teaching hospitals with a large bed size.

CONCLUSION

Approximately 1,535 TKAs have been performed in patients <21 years from 2000 to 2019 in the United States. The majority of these procedures were performed for reconstruction after resection of a malignant tumor. The rate of TKA for inflammatory arthritis/juvenile idiopathic arthritis has decreased over the past two decades.

Polyethylene Components in Primary Total Knee Arthroplasty: A Comprehensive Overview of Fixed Bearing Design Options

The articular design of a polyethylene insert influences the kinematics and overall function of a total knee arthroplasty (TKA). Standard symmetric posterior-stabilized and cruciate-retaining polyethylene designs have a long track record of high patient satisfaction and longevity in TKA. However, the number and variety of polyethylene inserts and articulations have continued to evolve in an attempt to better replicate native knee kinematics or provide additional constraint. Ultracongruent polyethylene designs have been touted as increasing stability while maintaining the benefits of cruciate-retaining knees. Medial pivot and lateral/dual pivot polyethylene designs were introduced to mimic more normal knee kinematics with regard to femoral rollback. Further, with increasing recognition of knee instability as a cause for persistent symptoms and revision TKA, the utilization of midlevel constraint polyethylene inserts has been increasing, with multiple implant companies offering an insert design with increased constraint for use with a primary femoral component. In this rapidly evolving arena in with a myriad of options available, surgeons should be knowledgeable about the design concepts and their applicable uses for specific patient scenarios. Future research is needed to better understand whether a particular type or design of polyethylene insert and articulation leads to improved patient reported outcomes, improved replication of knee kinematics, and long-term durable implant survivorship.

Arthroplasty Surgeons Differ in Their Intraoperative Soft Tissue Assessments: A Study in Human Cadavers to Quantify Surgical Decision-making in TKA

BACKGROUND

In TKA, soft tissue balancing is assessed through manual intraoperative trialing. This assessment is a physical examination via manually applied forces at the ankle, generating varus and valgus moments at the knee while the surgeon visualizes the lateral and medial gaps at the joint line. Based on this examination, important surgical decisions are made that influence knee stability, such as choosing the polyethylene insert thickness. Yet, the applied forces and the assessed gaps in this examination represent a qualitative art that relies on each surgeon's intuition, experience, and training. Therefore, the extent of variation among surgeons in conducting this exam, in terms of applied loads and assessed gaps, is unknown. Moreover, whether variability in the applied loads yields different surgical decisions, such as choice of insert thickness, is also unclear. Thus, surgeons and developers have no basis for deciding to what extent the applied loads need to be standardized and controlled during a knee balance exam in TKA.

QUESTIONS/PURPOSES

(1) Do the applied moments in soft tissue assessment differ among surgeons? (2) Do the assessed gaps in soft tissue assessment differ among surgeons? (3) Is the choice of insert thickness associated with the applied moments?

METHODS

Seven independent human cadaveric nonarthritic lower extremities from pelvis to toe were acquired (including five females and two males with a mean age of 73 ± 7 years and a mean BMI of 25.8 ± 3.8 kg/m 2 ). Posterior cruciate ligament substituting (posterior stabilized) TKA was performed only on the right knees. Five fellowship-trained knee surgeons (with 24, 15, 15, 7, and 6 years of clinical experience) and one chief orthopaedic resident independently examined soft tissue balance in each knee in extension (0° of flexion), midflexion (30° of flexion), and flexion (90° of flexion) and selected a polyethylene insert based on their assessment. Pliable force sensors were wrapped around the leg to measure the loads applied by each surgeon. A three-dimensional (3D) motion capture system was used to measure knee kinematics and a dynamic analysis software was used to estimate the medial and lateral gaps. We assessed (1) whether surgeons applied different moments by comparing the mean applied moment by surgeons in extension, midflexion, and flexion using repeated measures (RM)-ANOVA (p < 0.05 was assumed significantly different); (2) whether surgeons assessed different gaps by comparing the mean medial and lateral gaps in extension, midflexion, and flexion using RM-ANOVA (p < 0.05 was assumed significantly different); and (3) whether the applied moments in extension, midflexion, and flexion were associated with the insert thickness choice using a generalized estimating equation (p < 0.05 was assumed a significant association).

RESULTS

The applied moments differed among surgeons, with the largest mean differences occurring in varus in midflexion (16.5 Nm; p = 0.02) and flexion (7.9 Nm; p < 0.001). The measured gaps differed among surgeons at all flexion angles, with the largest mean difference occurring in flexion (1.1 ± 0.4 mm; p < 0.001). In all knees except one, the choice of insert thickness varied by l mm among surgeons. The choice of insert thickness was weakly associated with the applied moments in varus (β = -0.06 ± 0.02 [95% confidence interval -0.11 to -0.01]; p = 0.03) and valgus (β = -0.09 ± 0.03 [95% CI -0.18 to -0.01]; p= 0.03) in extension and in varus in flexion (β = -0.11 ± 0.04 [95% CI -0.22 to 0.00]; p = 0.04). To put our findings in context, the greatest regression coefficient (β = -0.11) indicates that for every 9-Nm increase in the applied varus moment (that is, 22 N of force applied to the foot assuming a shank length of 0.4 m), the choice of insert thickness decreased by 1 mm.

CONCLUSION

In TKA soft tissue assessment in a human cadaver model, five surgeons and one chief resident applied different moments in midflexion and flexion and targeted different gaps in extension, midflexion, and flexion. A weak association between the applied moments in extension and flexion and the insert choice was observed. Our results indicate that in the manual assessment of soft tissue, changes in the applied moments of 9 and 11 Nm (22 to 27 N on the surgeons' hands) in flexion and extension, respectively, yielded at least a 1-mm change in choice of insert thickness. The choice of insert thickness may be more sensitive to the applied moments in in vivo surgery because the surgeon is allowed a greater array of choices beyond insert thickness.

CLINICAL RELEVANCE

Among five arthroplasty surgeons with different levels of experience and a chief resident, subjective soft tissue assessment yielded 1 to 2 mm of variation in their choice of insert thickness. Therefore, developers of tools to standardize soft tissue assessment in TKA should consider controlling the force applied by the surgeon to better control for variations in insert selection.

A Mid-Level Constrained Insert Reduces Coupled Axial Rotation but Not Coronal Mid-Flexion Laxity Induced by Joint Line Elevation in Posterior-Stabilized Total Knee Arthroplasty: A Computational Study

BACKGROUND

Surgeons may resect additional distal femur during primary posterior-stabilized (PS) total knee arthroplasty (TKA) to correct a flexion contracture. However, the resultant joint line elevation (JLE) increases mid-flexion laxity. We determined whether a mid-level constraint (MLC) insert reduced mid-flexion laxity after JLE.

METHODS

Six computational knee models were developed using computed tomography scans and average soft tissue properties yielding balanced extension gaps but with a 10° flexion contracture. Distal femoral resections of +2 and +4 mm were simulated with PS and MLC inserts. Varus-valgus ±10 Nm moments were applied at 30°, 45°, and 60° of flexion. Coronal laxity (the sum of varus-valgus angulation) and coupled axial rotation (the sum of internal/external rotation) were measured and compared between insert models.

RESULTS

At 30° of flexion, coronal laxities with the PS insert at the +2 and +4 mm resections averaged 7.9° ± 0.6° and 11.3° ± 0.6°, respectively, and decreased by 0.8° (P = .06) and 1.0° (P = .07), respectively, with the MLC insert. PS rotational laxities at the +2 and +4 mm resections averaged 11.1° ± 3.9° and 12.5° ± 4.6°, respectively, and decreased by 5.6° (P = .01) and 7.1° (P = .02), respectively, with the MLC insert. Similar patterns were observed at 45° and 60° of flexion.

CONCLUSION

With additional distal femoral resections to alleviate a flexion contracture, utilizing an MLC insert substantially reduced coupled axial rotation but had a minimal impact on coronal laxity compared to a PS insert. Efforts should be taken to avoid JLE in primary total knee arthroplasty as even MLC inserts may not mitigate coronal laxity.

Decreased Implant Survival is Associated With Younger Patients Undergoing Total Knee Arthroplasty

Background: Younger patients are undergoing total knee arthroplasty (TKA) at increasing rates and may face multiple revisions during their lifetimes due to mechanical complications or infections. Questions/Purposes: We sought to compare the early complication rates and revision-free implant-survival rates across age groups of patients undergoing TKA, with particular focus on implant survival in younger patients. Methods: We conducted a retrospective analysis of data taken from a national insurance database on patients who underwent primary TKA from 2007 to 2015. Kaplan-Meier curve survival analysis and log rank test were performed to evaluate revision rates in 7 age groups (younger than 40, 40-49, 50-59, 60-69, 70-79, 80-89, and 90 or more years of age). Complication rates were compared to rates in the age 60 to 79 years age groups using multiple logistic regression, controlling for baseline demographics and comorbidities. Results: There were 114,698 patients included in the analysis. Patients in the younger than 40 years, 40 to 49 years, and 50 to 59 years age groups had increased rates of early mechanical complications; 90-day readmission rates were significantly higher in those age groups as well. Revision-free implant survival at 5 years was significantly worse in patients younger than 60 years of age, particularly those less than 40 years, who had a 77% revision-free implant-survival rate at 5 years. Conclusions: Younger patients had a higher risk of early revision after TKA, as well as an increased rate of mechanical complications and readmissions at 90 days. These outcomes suggest more study is needed to better understand these discrepancies and to better guide preoperative counseling for young patients considering TKA.

Satisfaction With the Process vs Outcome of Care in Total Hip and Knee Arthroplasty

BACKGROUND

Patient satisfaction, with both process of care and outcome of care, is critical for measuring the quality and value of elective procedures such as arthroplasty. The purpose of this study is to evaluate the correlation between early postoperative satisfaction with the process of care and 2-year satisfaction with the outcome of care after total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

We retrospectively analyzed data from institutional arthroplasty registries. Satisfaction with the outcome of care was measured on a scale of 0-100 by a previously validated questionnaire administered 2 years postoperatively. Patient satisfaction with the process of care was measured by the Press Ganey (PG) inpatient survey, also scored 0-100. We examined the correlation between these 2 measures of satisfaction in patients who underwent primary THA or TKA.

RESULTS

In total, 721 TKA patients and 760 THA patients underwent surgery and completed both the PG survey and 2-year satisfaction questionnaire. The mean age was 65.1 years with a mean body mass index of 28.8 and 56% were female. The mean PG survey score for the entire cohort was 95.6. The mean 2-year satisfaction score was 90.3. The Spearman correlation coefficient between the PG survey and the 2-year satisfaction survey was 0.23 for TKA patients (P < .001) and 0.13 for THA patients (P < .001).

CONCLUSION

We found a weak correlation between the measurement of satisfaction with the process of care surrounding hip and knee arthroplasty using the PG survey and measurement of satisfaction with the outcome of care after arthroplasty using a validated 2-year satisfaction instrument.

Obesity Does Not Affect Patient-Reported Outcomes following Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) has garnered attention in recent years as an effective alternative to total knee arthroplasty for patients with symptomatic, isolated patellofemoral joint arthritis. Obesity has previously been identified as a risk factor for revision surgery, but its effect on patient-reported outcome measures (PROMs) has not been evaluated. A retrospective review of a consecutive series of PFA surgeries was conducted at a single, specialized orthopedics center in a major urban center. Patients were dichotomized by body mass index (BMI) as obese (O, BMI >30) or nonobese (NO, BMI: 18.5-25). Demographic, surgical information, and PROMs were collected and analyzed accordingly. Seventy-six patients (41 nonobese, 35 obese) were identified. Patients who were obese presented with significantly worse preoperative PROMs regarding knee-specific quality of life, physical function, and MH or mental health (knee injury and osteoarthritis outcome score quality of life [KOOS QoL], NO: 26.2, O: 14.7, p = 0.019; KOOS PF, NO: 38.2, O: 50.5, p = 0.002; Veterans Rand-12 mental health [VR-12 MH], NO: 54.2, O: 47.0, p = 0.033). No significant difference was seen in improvement in knee function scores between patients who were obese or nonobese (KOOS QoL, NO: 39.5, O: 40.6, p = 0.898; KOOS PS [physical function], NO: -17.8, O: -17.3, p = 0.945). Additionally, no difference in the rate of PFA revision was observed and there were no postoperative complications reported. Obese patients with isolated PFA can expect the same improvement in function as nonobese patients following patellofemoral joint arthroplasty. This paper underscores the priority of patient selection in PFA and challenges the notion that surgeons should exclude patients from receiving a PFA on the basis of obesity.

Use of Total Hip Arthroplasty in Patients Under 21 Years Old: A US Population Analysis

BACKGROUND

The purpose of this study is to evaluate trends in the use of total hip arthroplasty (THA) in the United States in patients under 21 years of age. Specifically, we examined the frequency of THA in this patient population over the past 2 decades, the epidemiologic characteristics of patients under 21 who underwent THA, and the characteristics of the hospitals where these procedures were performed.

METHODS

We retrospectively reviewed the Kids' Inpatient Database, an inpatient US national weighted sample of hospital admissions in patients under 21 from approximately 4200 hospitals in 46 states. We queried the database using Current Procedural Terminology codes for elective and non-elective primary THA for the years 2000-2016. We utilized the International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes to determine primary diagnoses.

RESULTS

The weighted total number of THAs performed in patients under 21 in the Kids' Inpatient Database increased from 347 in 2000 to 551 in 2016. The most common diagnoses were osteonecrosis, osteoarthritis, and inflammatory arthritis. The frequency of THA for osteonecrosis increased from 24% in 2000 to 38% in 2016, while the frequency of THA for inflammatory arthritis decreased from 27% in 2000 to 4% in 2016.

CONCLUSION

The number of THAs in patients under 21 in the United States has increased over the past 2 decades and these procedures are increasingly performed in urban teaching hospitals. The decrease in THA for inflammatory arthritis in this population likely reflects improvements in medical management during the study period.

High Satisfaction and Activity Levels After Total Hip Arthroplasty in Patients Under Age 21

BACKGROUND

With improved materials and bearing surfaces, the use of total hip arthroplasty (THA) in young patients is increasing. Functional outcomes and activity level are particularly relevant in this higher-demand patient population. There is a paucity of data on patient-reported outcomes and activity levels after THA in extremely young (<21 years old) patients.

METHODS

We identified 196 patients (222 hips) who underwent THA at age <21 years at our institution from 1982 to 2018. After applying exclusion criteria, 113 of 160 (70.6%) patients (129 hips) were available for follow-up. Patient activity levels and functional outcomes were evaluated using the UCLA activity score, Forgotten Joint Score (FJS), Hip Disability and Osteoarthritis Outcome Score for Joint Replacement, and a validated 5-question satisfaction survey. Survivorship and reasons for revision were recorded.

RESULTS

The mean age at surgery was 17.0 ± 2.8 years, and the mean follow-up was 13.2 years (range 2-38 years). The most common indications for THA were osteonecrosis (34%) and juvenile idiopathic arthritis (30%). The mean UCLA activity score was 5.9 ± 2.0, and 64% of patients reported a score ≥6. The mean FJS was 57.9 ± 31.0. The mean Hip Disability and Osteoarthritis Outcome Score for Joint Replacement score was 84.6 ± 16.6. Ninety percent of patients reported that they were very or somewhat satisfied with their surgery. At final follow-up, 27 of 129 (20.9%) hips had undergone revision surgery.

CONCLUSION

THA performed in patients under 21 years of age with end-stage hip disease allows for high levels of activity and satisfaction postoperatively, with most patients being able to participate in moderate recreational activities. These data may be useful for surgeons in planning for and counseling extremely young patients indicated for THA.

Artificial neural network prediction of same-day discharge following primary total knee arthroplasty based on preoperative and intraoperative variables

AIMS

This study used an artificial neural network (ANN) model to determine the most important pre- and perioperative variables to predict same-day discharge in patients undergoing total knee arthroplasty (TKA).

METHODS

Data for this study were collected from the National Surgery Quality Improvement Program (NSQIP) database from the year 2018. Patients who received a primary, elective, unilateral TKA with a diagnosis of primary osteoarthritis were included. Demographic, preoperative, and intraoperative variables were analyzed. The ANN model was compared to a logistic regression model, which is a conventional machine-learning algorithm. Variables collected from 28,742 patients were analyzed based on their contribution to hospital length of stay.

RESULTS

The predictability of the ANN model, area under the curve (AUC) = 0.801, was similar to the logistic regression model (AUC = 0.796) and identified certain variables as important factors to predict same-day discharge. The ten most important factors favouring same-day discharge in the ANN model include preoperative sodium, preoperative international normalized ratio, BMI, age, anaesthesia type, operating time, dyspnoea status, functional status, race, anaemia status, and chronic obstructive pulmonary disease (COPD). Six of these variables were also found to be significant on logistic regression analysis.

CONCLUSION

Both ANN modelling and logistic regression analysis revealed clinically important factors in predicting patients who can undergo safely undergo same-day discharge from an outpatient TKA. The ANN model provides a beneficial approach to help determine which perioperative factors can predict same-day discharge as of 2018 perioperative recovery protocols. Cite this article: Bone Joint J 2021;103-B(8):1358-1366.

Trends in Utilization of Total and Unicompartmental Knee Arthroplasty in the United States

Total knee replacement (TKR) and unicompartmental knee replacement (UKR) are successful procedures for patients with knee arthritis. While strict criteria were proposed early on for UKR, some surgeons have expanded these indications to include younger and heavier patients. The purpose of this study is to analyze trends in usage of TKR and UKR in the United States. This retrospective study analyzed an insurance administrative dataset. Patients who underwent primary TKR and UKR were identified via current procedural terminology codes. Information on incidence, obesity, use of computer navigation, and surgical setting were collected. We analyzed 7,194 UKRs and 128,849 TKRs performed from 2007 to 2016. Prevalence of obesity in both groups increased over the study period. Utilization of computer navigation increased for UKR but declined for TKR. The rate of outpatient procedures significantly increased for UKR but remained constant for TKR. Both TKR and UKR are being performed at increasing rates and on heavier patients. The use of computer navigation and outpatient surgical setting is increasing for UKR but not for TKR. Knowledge of these trends is important for surgeons and policy-makers to help inform surgical indications and resource allocation.

Retrieval Analysis of Polyethylene Components in Rotating Hinge Knee Arthroplasty Implants

BACKGROUND

This study examined a cohort of retrieved rotating hinge (RH) total knee arthroplasty implants of four different designs with emphasis on the surface damage observed on the polyethylene components. Our purpose was to determine if differences in polyethylene damage existed among the designs, and if those differences could be explained by differences in design characteristics.

MATERIALS AND METHODS

Seventy-two RH implants from four manufacturers (DePuy LPS/SROM, Zimmer NexGen, Stryker Howmedica MRH, and Biomet Finn-OSS) removed at the time of revision performed between 2002 and 2017 were identified in our institutional retrieval registry. Damage to the surfaces of the polyethylene was assessed using a subjective grading system and evaluated in multiple zones. Design characteristics that were evaluated included the following: location of the dwell point on the polyethylene component, posterior position of the axle, and amount of hyperextension and rotation allowed by the implant.

RESULTS

There were no differences in total damage scores between the four implant groups (P = .45). The Stryker Howmedica MRH group showed the least backside wear of all implants but significantly more articular-sided wear compared with two of the other three groups. All implants except NexGen showed increased total damage scores in implants revised for mechanical (vs nonmechanical) reasons and in implants with a longer duration of implantation.

CONCLUSION

No single implant design emerged as superior in terms of minimizing polyethylene wear damage. Polyethylene damage existed in various locations but was not different in severity across designs, suggesting that there is no clear superior RH design that minimizes overall articular surface wear compared with other designs.

Additional distal femoral resection increases mid-flexion coronal laxity in posterior-stabilized total knee arthroplasty with flexion contracture : a computational study

AIMS

Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity.

METHODS

Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion.

RESULTS

With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline.

CONCLUSION

With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J 2021;103-B(6 Supple A):87-93.

Differences in time to return to work among patients undergoing simultaneous versus staged bilateral total knee arthroplasty

AIMS

Many patients undergoing total knee arthroplasty (TKA) have severe osteoarthritis (OA) in both knees and may consider either simultaneous or staged bilateral TKA. The implications of simultaneous versus staged bilateral TKA for return to work are not well understood. We hypothesized that employed patients who underwent simultaneous bilateral TKA would have significantly fewer days missed from work compared with the sum of days missed from each operation for patients who underwent staged bilateral TKA.

METHODS

The prospective arthroplasty registry at the Hospital for Special Surgery was used. Baseline characteristics and patient-reported outcome scores were evaluated. We used a linear regression model, adjusting for potential confounding variables including age, sex, preoperative BMI, and type of work (sedentary, moderate, high activity, or strenuous), to analyze time lost from work after simultaneous compared with staged bilateral TKA.

RESULTS

We identified 152 employed patients who had undergone simultaneous bilateral TKA and 61 who had undergone staged bilateral TKA, and had completed the registry's return to work questionnaire. The simultaneous group missed a mean of 46.2 days (SD 29.1) compared with the staged group who missed a mean total of 68.0 days of work (SD 46.1) when combining both operations. This difference was statistically significant (p < 0.001). In multivariate mixed regression analysis adjusted for age, sex, BMI, American Society of Anesthesiologists status, and type of work, the simultaneous group missed a mean of 16.9 (SD 5.7) fewer days of work compared with the staged group (95% confidence interval 5.8 to 28.1; p = 0.003).

CONCLUSION

Employed patients undergoing simultaneous bilateral TKA missed a mean of 17 fewer days of work as a result of their surgical treatment and rehabilitation compared with those undergoing staged bilateral TKA. This information may be useful to surgeons counselling employed patients with bilateral OA of the knee who are considering surgical treatment. Cite this article: Bone Joint J 2021;103-B(6 Supple A):108-112.

Simulation of preoperative flexion contracture in a computational model of total knee arthroplasty: Development and evaluation

Preoperative flexion contracture is a risk factor for patient dissatisfaction following primary total knee arthroplasty (TKA). Previous studies utilizing surgical navigation technology and cadaveric models attempted to identify operative techniques to correct knees with flexion contracture and minimize undesirable outcomes such as knee instability. However, no consensus has emerged on a surgical strategy to treat this clinical condition. Therefore, the purpose of this study was to develop and evaluate a computational model of TKA with flexion contracture that can be used to devise surgical strategies that restore knee extension and to understand factors that cause negative outcomes. We developed six computational models of knees implanted with a posteriorly stabilized TKA using a measured resection technique. We incorporated tensions in the collateral ligaments representative of those achieved in TKA using reference data from a cadaveric experiment and determined tensions in the posterior capsule elements in knees with flexion contracture by simulating a passive extension exam. Subject-specific extension moments were calculated and used to evaluate the amount of knee extension that would be restored after incrementally resecting the distal femur. Model predictions of the extension angle after resecting the distal femur by 2 and 4 mm were within 1.2° (p ≥ 0.32) and 1.6° (p ≥ 0.25), respectively, of previous studies. Accordingly, the presented computational method could be a credible surrogate to study the mechanical impact of flexion contracture in TKA and to evaluate its surgical treatment.

A geometric ratio to predict the flexion gap in total knee arthroplasty

Measured resection is a common technique for obtaining symmetric flexion and extension gaps in posterior-stabilized (PS) total knee arthroplasty (TKA). A known limitation of measured resection, however, is its reliance on osseous landmarks to guide bone resection and component alignment while ignoring the geometry of the surrounding soft tissues such as the medial collateral ligament (MCL), a possible reason for knee instability. To address this clinical concern, we introduce a new geometric proportion, the MCL ratio, which incorporates features of condylar geometry and MCL anterior fibers. The goal of this study was to determine whether the MCL ratio can predict the flexion gaps and to determine whether a range of MCL ratio corresponds to balanced gaps. Six computational knee models each implanted with PS TKA were utilized. Medial and lateral gaps were measured in response to varus and valgus loads at extension and flexion. The MCL ratio was related to the measured gaps for each knee. We found that the MCL ratio was associated with the flexion gaps and had a stronger association with the medial gap (β = -7.2 ± 3.05, P < .001) than with the lateral gap (β = 3.9 ± 7.26, P = .04). In addition, an MCL ratio ranging between 1.1 and 1.25 corresponded to balanced flexion gaps in the six knee models. Future studies will focus on defining MCL ratio targets after accounting for variations in ligament properties in TKA patients. Our results suggest that the MCL ratio could help guide femoral bone resections in measured resection TKA, but further clinical validation is required.

Assessment of a Satisfaction Measure for Use After Primary Total Joint Arthroplasty

BACKGROUND

Patient satisfaction after total hip (THA) and total knee arthroplasty (TKA) is a core outcome selected by the Outcomes Measurement in Rheumatology. Up to 20% of THA/TKA patients are dissatisfied. Improving patient satisfaction is hindered by the lack of a validated measurement tool that can accurately measure change.

METHODS

The psychometric properties of a proposed satisfaction instrument, consisting of 4 questions rated on a Likert scale, scored 1-100, were tested for validity, reliability, and sensitivity to change using data collected between 2007 and 2011 in an arthroplasty registry.

RESULTS

We demonstrated construct validity by confirming our hypothesis; satisfaction correlated with similar constructs. Satisfaction correlated moderately with pain relief (TKA ρ = 0.61, THA ρ = 0.47) and function (TKA ρ = 0.65, THA ρ = 0.51) at 2 years; there was no correlation with baseline/preoperative pain/function values, as expected. Overall Cronbach's alpha >0.88 confirmed internal consistency. Test-retest reliability with weighted kappa ranged 0.60-0.75 for TKA and 0.36-0.56 for THA. Hip disability and Osteoarthritis Outcome Score/Knee injury and Osteoarthritis Outcome Scores quality of life improvement (>30 points) corresponds to a mean satisfaction score of 93.2 (standard deviation, 11.5) after THA and 90.4 (standard deviation, 13.8) after TKA, and increasing relief of pain and functional improvement increased the strength of their association with satisfaction. The satisfaction measure has no copyright and is available free of cost and represents minimal responder burden.

CONCLUSION

Patient satisfaction with THA/TKA can be measured with a validated 4-item questionnaire. This satisfaction measure can be included in a total joint arthroplasty core measurement set for total joint arthroplasty trials.

Early failure of a modern moderately cross-linked polyethylene acetabular liner

Modern polyethylene components for total hip arthroplasty have shown excellent long-term wear properties. However, among 204 primary total hip arthroplasty procedures performed by one surgeon using the Exactech Connexion GXL Liner, we identified 5 cases of severe polyethylene wear and osteolysis which occurred within 5 years of the index surgery. Among the 5 cases, all patients had a size 36 head with an acetabular component from size 52 to 56 mm. All patients had a UCLA activity scale score of at least 6 at the time that the osteolysis was detected. The average wear rate was 0.265 mm ± 0.207 mm per year. This review of 5 cases of catastrophic early polyethylene wear demonstrates a concerning trend with the use of the Exactech Connexion GXL liner. Further investigation is warranted to evaluate material characteristics which may have caused this accelerated wear and to prevent recurrences of this complication in the future.

Determining the Validity, Reliability, and Utility of the Forgotten Joint Score: A Systematic Review

BACKGROUND

With improving patient outcome after total hip and total knee arthroplasty, patient-reported outcome measures (PROMs) have seen a parallel rise in average scores and ceiling effects. The Forgotten Joint Score (FJS) is a PROM that has been previously proposed to reduce this observed ceiling effect. However, the validity and reliability of the FJS has not been well analyzed.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried using keywords pertinent to FJS, validity, reliability, measurement properties, and PROM. The methodological quality of measurement properties was evaluated using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist.

RESULTS

In total, 13 articles met the inclusion criteria and were included in this analysis. Internal consistency was consistently high (Cronbach alpha >0.9). Test-retest reliability was good or excellent (interclass correlation coefficient ≥0.8) in all studies. As for construct validity, all the articles reported a positive rating. Floor and ceiling effects overall were low (<15%). Conflicting results were found for responsiveness and measurement error.

CONCLUSION

There is a strong evidence of good construct validity and test-retest reliability regarding the FJS, with moderate evidence of good internal consistency. Ceiling and floor effects were very low, showing a very promising discriminatory power between patients with a good outcome and patients with an excellent outcome. Therefore, especially in patients expected to achieve high levels of function after total joint replacement, we highly recommend the use of FJS for the long-term assessment of their treatment.

Extended Antibiotic Prophylaxis May Be Linked to Lower Peri-prosthetic Joint Infection Rates in High-Risk Patients: An Evidence-Based Review

In 2018, Inabathula et al. published the results of a historical control study examining 90-day peri-prosthetic joint infection (PJI) rates at a single center before and after the institution of an extended post-operative oral antibiotic protocol for high-risk total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients. In the study, "Extended Oral Antibiotic Prophylaxis in High-Risk Patients Substantially Reduces Primary Total Hip and Knee Arthroplasty 90-Day Infection Rate" (J Bone Joint Surg Am. 2018;100[24]:2103-2109), the authors considered any one of several patient-related criteria-including diabetes, a body mass index of 35 kg/m² or higher, or active smoking-as sufficient to designate a patient "high risk" for PJI. Before the extended antibiotic therapy protocol was instituted, PJI rates for primary THA and TKA in the high-risk subgroup were 4.3% and 2.1%, respectively. After it was instituted, the respective rates dropped to 1.1% and 0.4%, comparable to those seen in the non-high-risk patients treated using standard peri-operative prophylaxis. After adjusting for patient factors, regression analysis showed that high-risk patients receiving only peri-operative antibiotics were more likely to develop PJI than high-risk patients receiving the extended antibiotic protocol. Although these results suggest possible benefits of extended antibiotic prophylaxis in arthroplasty, methodologic limitations and inadequate discussion of potential drawbacks of widespread adoption of such protocols limit the impact of the findings. Future research is warranted to more narrowly define risk factors for PJI and to demonstrate the safety and efficacy of extended antibiotics in reducing the long-term burden of PJI.

Complications associated with staged versus simultaneous bilateral total knee arthroplasty: An analysis of 7747 patients

BACKGROUND

Benefits of simultaneous bilateral total knee replacement (TKR) include lower costs, decreased hospital stay, and shorter rehabilitation. This study evaluated complications associated with simultaneous versus staged bilateral TKR within 12 months. We hypothesized that after controlling for comorbidities, the simultaneous group would have the highest rate of complications.

METHODS

This retrospective study analyzed the Humana subset of the PearlDiver Patient Records Database. CPT 27447 and associated modifiers were used to identify patients who underwent simultaneous or staged bilateral primary TKRs. Staged bilateral TKRs were performed within 12 months and were stratified by the time between procedures. Primary outcomes were the Centers for Medicare & Medicaid Services' publicly reported complications. Risks of complications were compared using multivariate logistic regression controlling for age, gender, and comorbidities.

RESULTS

Seven thousand seven hundred forty-seven patients underwent simultaneous or staged bilateral TKRs between January 2007 and April 2015. There were lower odds of transfusion and all-cause 90-day readmission but higher odds of mechanical complications and infection for all staged groups compared to the simultaneous. Patients whose staged surgeries were ≪3 months apart had significantly higher odds of undergoing manipulation under anesthesia (MUA).

CONCLUSIONS

Higher rates of blood transfusion and readmission were associated with simultaneous bilateral TKR, while higher rates of mechanical complications and infection were associated with staged bilateral TKR. MUA risk was highest in patients staged ≪3 months apart. While there are inherent risks to simultaneous bilateral TKR, surgeons and patients should also be aware of risks associated with staging the procedures.

LEVEL OF EVIDENCE

III.

Patient satisfaction reporting for patellofemoral arthroplasty is significantly lacking: a systematic review

Background: Patellofemoral Arthroplasty (PFA) has been shown to be successful in restoring knee function and quality of life in patients with the isolated patellofemoral disease. Patient satisfaction has been suggested as an indicator of the quality of elective orthopedic operations, although there remains no standardized method to collect and evaluate satisfaction. The present study offers a systematic review of the available literature concerning patient satisfaction following PFA to assess common methodologies for reporting patient satisfaction. Methods: A query of the Medline database produced 116 articles that were reviewed for inclusion in the review. The following inclusion criteria were used to identify suitable articles: English language, clinical outcomes study related to PFA, and patient-reported satisfaction as an outcome measure. Results: Seven studies met inclusion criteria and were eligible for review. The highest level of evidence was level-III. The study publication dates ranged from 2009 to 2016, with six published in 2015 & 2016. In total, 320 PFAs were performed on 267 patients. Four articles reported the proportion of included patients who had previous knee surgeries (range: 20-60%). Three studies used ordinal scales to rate patient satisfaction. Four studies (57.1%) reported the numeric proportion of patients satisfied following PFA, which ranged from 76% to 96.5%. Two studies used Visual Analog Scale methods. For these two studies, one of them reported the mean satisfaction score as 7.5/10, and the other reported a median of 90/100. Conclusions: The available literature on patient satisfaction after PFA was found to be limited, with low-quality evidence and variable methodology.

Posterior condylar bone resection and femoral implant thickness vary by up to 3 mm across implant systems: implications for flexion gap balancing

PURPOSE

The purpose of this study was to evaluate the thickness of medial and lateral posterior femoral condylar bone resected with five implant systems using posterior referencing jigs set at 3° of external rotation. The hypothesis was that posterior condylar resection thickness on the medial side would be equal to the thickness of the femoral implant posteriorly, regardless of implant system.

METHODS

Posterior referencing femoral sizers were used on right femur sawbones models for five different implant systems. Each sawbones model was sized using a femoral sizer for the specific implant system. Sizing guides were set at 3° of external rotation for the right femur. Each system's 4-in-1 cutting block was then used to make posterior condylar cuts. The thicknesses of the cut bones were measured using a manual calliper.

RESULTS

The amount of bone resected from both medial (P = 0.0004) and lateral (P < 0.0001) posterior condyles differed significantly across the five implant systems. The mean thickness of bone resected from the posteromedial femoral condyle ranged from 9.4 ± 0.5 to 12.4 ± 0.9 mm. The mean thickness of the posterolateral condyle cut ranged from 6.7 ± 0.6 to 10.2 ± 0.3 mm. The difference in thicknesses between the bone resection from the posteromedial condyle and the implant thickness of the posterior condyles ranged from 0.6 to 2.9 mm.

CONCLUSIONS

The thickness of bone removed from the posterior femoral condyles varied by up to 3 mm across the five TKA implant systems. For each system, the posteromedial condyle resection was larger than the thickness of the posterior condyle of the actual implant. As the difference between the posterior bone resection and the implant thickness increases, the flexion gap will likely loosen and should be accounted for during gap balancing. In commonly used knee implant systems, resected bone is greater than implant thickness and may lead to flexion instability.

Causes of Revision in Young Patients Undergoing Total Hip Arthroplasty

BACKGROUND

The purpose of this study was to identify reasons for revision of total hip arthroplasty (THA) in patients who underwent primary THA at or before the age of 35 years. We hypothesized that the reasons for revision in younger patients would be different from the general older population of patients undergoing THA because of the differences in diagnoses, complexity of deformities, and differences in activity level.

METHODS

Data for 108 hips in 82 patients who underwent primary THA at our institution before the age of 35 years from 1982-2007 and subsequently underwent revision THA were reviewed. Operative reports and clinic notes were reviewed to determine baseline characteristics, reason for revision, timing of revision, and components revised.

RESULTS

The mean age at index surgery was 25.4 years, and mean time from index to revision surgery was 10.1 years. The most common preoperative diagnoses included avascular necrosis, juvenile idiopathic arthritis, developmental dysplasia of the hip, and posttraumatic arthritis. The most common reasons for revision were acetabular loosening (30.1%), femoral loosening (23.7%), and polyethylene wear (24.7%). 8.3% of patients underwent primary THA with highly cross-linked polyethylene, while the remainder of the patients underwent THA when conventional polyethylene was used. There was no statistically significant association between which component(s) were revised and initial fixation (ie cemented or uncemented prosthesis) (P = .26).

CONCLUSION

Causes of revision in this population appear to differ from the general THA population. In young patients, acetabular loosening, femur loosening, and polyethylene wear were the most common causes of revision. Instability and infection were less common compared with literature reports of causes of revision in older patients. Findings in this study may be useful in counseling young patients undergoing THA, though results were likely influenced by the use of conventional rather than highly cross-linked polyethylene in this cohort.

Inflammatory Arthritis Is a Risk Factor for Multiple Complications After Total Hip Arthroplasty: A Population-Based Comparative Study of 68,348 Patients

BACKGROUND

Patients with inflammatory arthritis (IA) are likely at higher risk of postoperative complications following total hip arthroplasty (THA), from the underlying disease, the degree of articular deformity, and immunosuppressive medications. The purpose of this study was to perform a comparative study of the risk of complications after THA between IA and osteoarthritis.

METHODS

A national private insurance database was used to select patients undergoing unilateral primary THA. Patients were categorized to the inflammatory cohort if they had a diagnosis of IA and treatment with an IA-specific medication within the year before surgery. Patients with no diagnosis of IA were considered osteoarthritis. Risk of Centers for Medicare and Medicaid Services-reportable complications and 90-day readmission was compared between cohorts using multivariate logistic regression controlling for age, gender, length of stay, comorbidities, and corticosteroid use.

RESULTS

A total of 68,348 patients were included; 2.12% met criteria for IA. Patients with IA were found to have higher risk of transfusion (odds ratio [OR], 1.29; P < .01), mechanical complications (OR, 1.35; P = .01), infection (OR, 1.96; P < .01), and 90-day readmission (OR, 1.35; P < .01). There were no differences in risk of venous thromboembolism or medical complications.

CONCLUSION

Patients with IA have significantly higher risk of transfusion, mechanical complications, infection, and readmission following THA. Efforts should be made to optimize their health and medications before THA to minimize their complication risk. Additionally, hospitals should receive commensurate resources to maintain access to THA for patients with IA who are prone to higher resource utilization.

LEVEL OF EVIDENCE

III.

Diagnosing Prosthetic Joint Infections in Patients With Inflammatory Arthritis: A Systematic Literature Review

BACKGROUND

Patients with inflammatory arthritis (IA) are at increased risk of prosthetic joint infections (PJI), yet differentiating between septic and aseptic failure is a challenge. The aim of our systematic review is to evaluate synovial biomarkers and their efficacy at diagnosing PJI in patients with IA.

METHODS

A comprehensive literature search was performed in the following databases from inception to January 2018: Ovid MEDLINE, Ovid EMBASE, and the Cochrane Library. Searches across the databases retrieved 367 results. Two of 5 reviewers independently screened a total of 298 citations. Discrepancies were resolved by a third reviewer. Twenty articles fit our criteria, but due to methodological differences findings could not be pooled for meta-analysis. For 5 studies, raw data were provided, pooled, and used to derive optimal diagnostic cut points.

RESULTS

Our final analysis included 1861 non-IA patients, including 426 patients with PJI, and 90 IA patients of whom 26 had PJI. There was a significant difference among the 4 groups for serum C-reactive protein (CRP), erythrocyte sedimentation rate, and synovial CRP, polymorphonuclear neutrophil percent, white blood cells, interleukin (IL)-6, IL-8, and IL-1b. Polymorphonuclear neutrophil percent had the highest sensitivity (95.2%) and specificity (85.0%) to detect infections with an optimum threshold of 78%.

CONCLUSION

While levels of synovial white blood cells, IL-6, IL-8, and serum CRP appear higher in patients with IA, there is overlap with those who are not infected. Further studies are needed to explore diagnostic tests that will better detect PJI in patients with IA.

Single- Versus Double-Row Repair of Hip Abductor Tears: A Biomechanical Matched Cadaver Study

PURPOSE

The purposes of this study were (1) to evaluate the percentage of gluteus medius and minimus tendon footprint restoration that can be achieved with fixation using single-row repair versus double-row repair and (2) to evaluate the yield load of a repair of the gluteus medius and minimus tendon using single-row versus double-row repair techniques.

METHODS

Twelve human fresh-frozen cadaveric hip specimens (6 matched pairs, 4 female, mean age 47.5 ± 14.5 years) were tested. Specimens were excluded if they had any prior hip surgery or injury, if any abnormality of the tendon was noted on dissection, or if they had a body mass index <20 or >35 or a T-score <2.0 on dual-energy x-ray absorptiometry scanning. Matched pairs were randomized to receive either double-row repair with 2 standard suture anchors and 2 knotless anchor devices or a single-row repair with suture anchors only. The percentage of the footprint area covered after repair was determined using a computer-assisted digitization algorithm. With a mechanical testing system, each repaired specimen was tested for mechanical strength first with cyclic loading and then load to failure testing.

RESULTS

Footprint coverage of the lateral facet was significantly greater for double-row repair (mean 76.6%) compared with single-row repair (mean 50.3%) (P = .03). There was no significant difference between single- and double-row repair for posterior-superior or anterior facet coverage. Mechanical testing showed a higher mean yield load for double-row anchor repair (197.6 ± 61.7 N vs 163.5 ± 35.4 N for single-row repair), but this did not reach statistical significance (P = .15). The predominant mode of failure was suture pullout through the musculotendinous unit (9/12 specimens: 5 double-row and 4 single-row).

CONCLUSIONS

For hip abductor tears, double-row suture repair yields improved footprint coverage compared with single-row repair. Although it did not reach statistical significance, there was a higher mean yield load in the double-row group.

CLINICAL RELEVANCE

Double-row suture fixation technique for hip abductor tears maximizes strength and footprint coverage of the repair.

A Novel Mobile Phone Text Messaging Platform Improves Collection of Patient-Reported Post-operative Pain and Opioid Use Following Orthopedic Surgery

BACKGROUND

Prospective collection of patient-reported opioid consumption and pain levels post-surgically may hold value in highlighting solutions related to the opioid crisis. Traditional methods for collecting patient-reported outcomes after surgery, such as paper surveys, often have poor response rates, and electronic messaging may offer more convenience and therefore yield more robust data.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate whether a novel mobile phone short message service (SMS) platform would lead to better patient response rates to surveys on pain and opioid use than data-collection tools.

METHODS

An SMS text messaging platform was created and implemented between September 2017 and May 2018 at an orthopedic specialty hospital. The purpose was to collect reports on opioid consumption and pain levels twice a day for 6 weeks post-surgery from patients who had undergone total hip or knee arthroplasty or a single-level lumbar microdiscectomy or decompression spine surgery. Patients who responded to fewer than 50% of the text messages were excluded.

RESULTS

Our mobile phone text messaging platform was used by 183 patients, demonstrating a significantly higher response rate (96.1%) than our institution's post-operative email registry capture, as well as the majority of published response rates for post-operative outcomes captured through electronic and traditional data-collection systems. Response rate remained consistently high among the various surgeons and across patients, regardless of age.

CONCLUSIONS

This application of a widely available technology can improve the measurement of post-operative patient-reported outcomes. Such data can in turn be used in the development of strategies to reduce post-operative opioid use. The adoption of novel technologies at a patient level will play a key role in combating the opioid epidemic.

Development of an Institutional Opioid Prescriber Education Program and Opioid-Prescribing Guidelines: Impact on Prescribing Practices

BACKGROUND

Our institution developed a 1-hour mandatory narcotics-prescribing education program as well as postoperative opioid-prescribing guidelines in response to the opioid epidemic. The purpose of this study was to evaluate the effect of this hospital-wide opioid education and subsequent institution of postoperative opioid guidelines on opioid-prescribing practices after ambulatory surgery.

METHODS

This retrospective study was performed at 1 academic orthopaedic hospital. In November 2016, a 1-hour mandatory opioid education program was completed by all hospital prescribers. Postoperative opioid guidelines were then developed and were disseminated in February 2017. All postoperative narcotic prescriptions after ambulatory procedures performed by 3 separate services (hand, sports, and foot and ankle services) were evaluated over 4 months prior to and after the mandatory opioid education and subsequent release of service-specific guidelines.

RESULTS

Overall, there was a significant decrease in pills and total oral morphine equivalents prescribed after dissemination of guidelines compared with the pre-intervention cohort procedures (p < 0.001) performed by the sports and hand services. With regard to the sports medicine service, the mean difference in pills prescribed was 6.47 pills (95% confidence interval [CI], 5.4 to 7.5 pills) for knee arthroscopy, 5.6 pills (95% CI, 2.5 to 8.7 pills) for shoulder arthroscopy, and 16.3 pills (95% CI, 13.6 to 19.1 pills) for hip arthroscopy. With regard to the hand service, the mean difference in pills prescribed was 13.0 pills (95% CI, 10.2 to 15.8 pills) for level-1 procedures, 12.4 pills (95% CI, 9.9 to 15.0 pills) for carpal tunnel release, and 21.7 pills (95% CI, 18.0 to 25.3 pills) for distal radial fractures. The decrease in pills prescribed in the post-intervention cohort amounts to almost 30,000 fewer opioid pills prescribed per year after these 6 procedures alone. There was no significant change (p > 0.05) in either the number of pills or the oral morphine equivalents prescribed after any of the 3 procedures performed by the foot and ankle service (ankle arthroscopy, bunion surgery, and Achilles tendon repair).

CONCLUSIONS

We developed a prescriber education program and followed up with consensus-based guidelines for postoperative opioid prescriptions. These interventions caused a significant decrease in excessive opioid-prescribing practices after ambulatory orthopaedic surgery at our hospital. We urge initiatives by national orthopaedic organizations to develop and promote education programs and procedure and disease-specific opioid-prescribing guidelines.

The Quality of Online Resources Available to Patients Interested in Knee Biologic Therapies Is Poor

BACKGROUND

As the use of biologic therapies for the management of knee pathology continues to expand, it is more likely that patients will turn to the Internet to gather information on this topic. Given the lack of scientific consensus on the use of biologics, care providers must understand what information is available online.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate the quality of websites that patients may use to educate themselves on knee biologics.

METHODS

Websites were identified using search terms relevant to multiple biologic therapies available for knee pathology. Websites were scored based on an author-derived grading rubric, with a total of 25 possible points relating to the role of knee biologics in the diagnosis, evaluation, and treatment of knee pathology. Websites were categorized based on the source (e.g., physician-operated website vs. industry-related website). Reading level was assessed with the Flesch-Kincaid readability test.

RESULTS

The initial search yielded 375 results, with 96 websites meeting final inclusion criteria. Mean website score was poor, at 6.01 of the 25 possible points (24.0%). Physician websites were the most common, with 60% of the articles identified. Industry-related websites scored the lowest (mean, 3.2 ± 0.97) while hospital-related websites scored the highest (mean, 8.3 ± 2.93). Overall, websites published from hospitals or orthopedic professional societies had significantly higher scores than other websites. The search term "knee PRP" yielded higher-quality results than "knee platelet rich plasma." Similarly, "knee BMAC" led to better results than "knee bone marrow aspirate concentrate." The average reading level was 11.4.

CONCLUSION

Many online resources are available for patients seeking information about knee biologic therapies, but the quality of websites identified was very poor. Patients should be counseled that the information available online for knee biologic therapy is unreliable. Surgeons should play an increased role in providing resources to patients and educating them on biologic options.

Type of Anticoagulant Used After Total Knee Arthroplasty Affects the Rate of Knee Manipulation for Postoperative Stiffness

BACKGROUND

The aim of this study was to perform a population-level analysis on the effect of different types of anticoagulation on postoperative stiffness after total knee replacement, requiring manipulation under anesthesia. We hypothesized that patients receiving warfarin would have a higher rate of manipulation under anesthesia compared with patients receiving low-molecular-weight heparin. We also hypothesized that aspirin, direct factor Xa inhibitors, and fondaparinux would have no effect on the rate of manipulation under anesthesia.

METHODS

Using the PearlDiver patient database, we analyzed 32,320 patients who underwent a primary unilateral total knee replacement from 2007 to 2015. Patients were included if they filled a prescription for anticoagulation medication within 2 days of their discharge and were excluded if they were taking a prescription anticoagulation medication (except for aspirin) in the 3 months before total knee replacement. The primary outcome was manipulation under anesthesia performed within 6 months after a primary total knee replacement.

RESULTS

The most commonly prescribed postoperative anticoagulation was warfarin (38.0%), followed by low-molecular-weight heparin (33.8%). There were 1,178 patients (3.64%) who underwent manipulation under anesthesia within 6 months of total knee replacement. In multivariable analysis using low-molecular-weight heparin as a comparison group and accounting for age, sex, comorbidities, and length of stay, there was a significant increase in the risk of manipulation under anesthesia for patients who received warfarin (hazard ratio [HR], 1.17 [95% confidence interval (CI), 1.01 to 1.36]; p = 0.032), direct factor Xa inhibitors (HR, 1.42 [95% CI, 1.20 to 1.66]; p < 0.001), or fondaparinux (HR, 1.33 [95% CI, 1.01 to 1.72]; p = 0.038). Although patients who received aspirin had the same risk estimate as patients who received warfarin, there was not a significantly increased risk of manipulation under anesthesia in patients who received aspirin compared with low-molecular-weight heparin (HR, 1.17 [95% CI, 0.72 to 1.80]; p = 0.493).

CONCLUSIONS

We found an increased rate of manipulation under anesthesia after total knee replacement in patients who received oral anticoagulants including warfarin, direct factor Xa inhibitors, and fondaparinux, in comparison with patients who received aspirin or low-molecular-weight heparin. We recommend that patients receiving oral anticoagulants after total knee replacement should be counseled about associated stiffness. Furthermore, surgeons should take these data into account when selecting thromboprophylaxis for patients after total knee replacement.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Patient Satisfaction After Total Knee Replacement: A Systematic Review

BACKGROUND

The quality and state of satisfaction reporting after total knee replacement (TKR) is variable.

QUESTIONS/PURPOSES

The purposes of this systematic review were (1) to examine the available literature on patient satisfaction after TKR, (2) to evaluate the quality of available evidence, and (3) to identify predictors of patient satisfaction after TKR.

METHODS

A systematic review of the MEDLINE database was performed. The initial search yielded 1219 studies. The inclusion criteria were English language, clinical outcome study with primary outcome related to TKR for osteoarthritis, and patient-reported satisfaction included as an outcome measure. Studies were assessed for demographics, methodology for reporting satisfaction, and factors influencing satisfaction.

RESULTS

Two hundred eight studies, including 95,560 patients who had undergone TKR, met all inclusion and exclusion criteria; 112 (53.8%) of these studies were published in the past 3 years. Satisfaction was most commonly measured using an ordinal scale. Twenty-seven studies (13%) used a validated satisfaction survey. Eighty-three percent of studies reported more than 80% satisfaction. The most commonly reported predictor of satisfaction was post-operative patient-reported functional outcome. Pre-operative anxiety/depression was the most common pre-operative predictor of dissatisfaction.

CONCLUSION

There are numerous studies reporting patient satisfaction after TKR, and publication on the topic has been increasing over the past decade. However, the majority of studies represent lower levels of evidence and use heterogeneous methods for measuring satisfaction, and few studies use validated satisfaction instruments. In general, the majority of studies report satisfaction rates ranging from 80 to 100%, with post-operative functional outcome and relief of pain being paramount determinants for achieving satisfaction.

Rates and Risk Factors of Conversion Hip Arthroplasty After Closed Reduction Percutaneous Hip Pinning for Femoral Neck Fractures-A Population Analysis

BACKGROUND

Closed reduction with percutaneous pinning (CRPP) for nondisplaced or valgus impacted femoral neck fractures is a relatively low-risk operation that can produce excellent union rates in some patients; however, failure can occur in selected patients requiring conversion to arthroplasty. The primary aim of this study was to perform a population-level analysis to determine the rate and timeframe of conversion from CRPP to total hip arthroplasty (THA) or hemiarthroplasty.

METHODS

The PearlDiver database was queried from 2007-2015 for all patients who underwent CRPP for a femoral neck fracture. Survival analysis was used to evaluate the rate of conversion of CRPP to hemiarthroplasty or THA. Risk factors for conversion arthroplasty were identified using a multivariable cox proportional hazards model that included patient demographics and comorbidities.

RESULTS

There were 5122 patients in the Humana database and 4840 patients in the Medicare database that were included in analysis. At 5 years after CRPP, the conversion rate was 10.0% in the Medicare patients and 10.8% in the Humana patients. Risk factors for undergoing conversion from CRPP to arthroplasty in the Medicare cohort included preexisting diagnoses of pulmonary and/or circulatory comorbidities, peripheral vascular disease, hypertension, hypothyroidism, and metastatic cancer. In the Humana cohort, the only risk factors were male gender and acute blood loss anemia.

CONCLUSION

Although CRPP remains a successful operation in elderly patients and patients with certain comorbidities, failure of CRPP for the treatment of a femoral neck fracture is high at approximately 10%-11%, which is much higher than reported failure rates for THA in the same population. Patients with femoral neck fractures being considered for CRPP should be counseled about the possibility of further surgery.

Preoperative Valgus Alignment Does Not Predict Inferior Outcome of Total Knee Arthroplasty

BACKGROUND

Preoperative valgus deformity is present in an estimated 10-20% of patients undergoing total knee replacement (TKR).

QUESTIONS/PURPOSES

The objective of this study was to compare the Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores after TKR in a matched cohort of patients with preoperative valgus and varus deformities.

METHODS

This is a matched cohort study of 162 patients with varus native knees and 162 patients with valgus native knees who underwent TKR and were prospectively followed in our institutional registry. Patients matched were based on age, BMI, sex, and severity of preoperative knee deformity, which was classified as mild, moderate, severe varus or valgus, or no deformity. Outcomes were evaluated using the WOMAC preoperatively and at 6 weeks, 3 months, 6 months, and 1 year postoperatively.

RESULTS

No significant difference was found between the matched varus and valgus cohorts in all WOMAC subdomain scores except for a marginally worse stiffness at 1 year in patients with valgus deformity (WOMAC stiffness, 75.1 varus vs. 70.1 valgus; P = 0.049). This is below the minimal clinically important difference for WOMAC scores. There was no significant difference in postoperative varus/valgus alignment between the two groups (P = 0.092).

CONCLUSION

We found no clinically significant difference in any of the WOMAC domains in patients with preoperative varus deformity versus valgus deformity within the first year after TKR. These findings may allow surgeons to more appropriately counsel patients with osteoarthritis with valgus deformity that they can expect similar outcomes compared to patients with varus deformity.

What is the Quality of Online Resources About Pain Control After Total Knee Arthroplasty?

BACKGROUND

With the growing opioid crisis in the United States, there has been a push to reduce the utilization of opioids in favor of multimodal analgesia options. The purpose of this study was to evaluate the quality of online resources that patients may use to learn about pain control after total knee arthroplasty (TKA).

METHODS

We identified websites using a combination of search terms about TKA and pain control. A novel grading rubric was created with 25 maximum points, consisting of items that were deemed important for patients to know about the subject. Three authors then independently graded websites and the results averaged. Flesch-Kinkaid reading level was also evaluated.

RESULTS

After identifying 166 unique websites, 32 met final inclusion criteria. The overall scores were low-4.7 of 25 total points (18.8%), written at an average 10th grade level. Subgroup scores were 50% for route of administration, 40% for types of analgesia, 23% for opioid-specific items, and 30% for general guidance. Only about half discussed the risks of opioid dependency. The top 3 website total scores ranged from 10.7-12.5 of 25 points.

CONCLUSION

There is a paucity of online information for TKA patients to read about pain control. Most websites provide limited educational content, particularly about opioids. Higher quality information is needed to help patients make decisions with their physicians and to help combat the opioid epidemic. Given the lack of quality information available, there is an opportunity for subspecialty organizations to take a leadership role in such efforts.

Arthroscopic Treatment of Femoroacetabular Impingement in Adolescents Provides Clinically Significant Outcome Improvement

PURPOSE

To define minimal clinically important difference (MCID) and substantial clinical benefit (SCB) for adolescents undergoing arthroscopic femoroacetabular impingement (FAI) surgery.

METHODS

A prospective institutional hip preservation registry was reviewed to identify hip arthroscopies performed for FAI. Patients with pre-existing hip conditions such as slipped capital femoral epiphysis and Legg-Calve-Perthese were excluded. Included patients were 18 years and younger. The modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS), and the international Hip Outcome Tool (iHOT-33) were administered as part of the registry. MCID was calculated using a distribution-based method, and SCB was calculated using a physical function anchor question. Receiver operating characteristic analysis with area under the curve (AUC) was used for psychometric analyses.

RESULTS

Forty-seven adolescents were identified. The majority of patients were female (n = 32, 68.1%) with a mean age of 16.5 (±1.1) years. The MCID (% achieving) for the mHHS, HOS activities of daily living (ADL), HOS Sport, and iHOT-33 was 9.5 (85%), 9.8 (79%), 12.1 (85%), and 10.7 (94%), respectively. Ninety-two percent of adolescents reported some form of improved hip physical ability on the anchor question. The following 1-year absolute outcome scores were significantly representative of an SCB state on the mHHS, HOS ADL, HOS Sport, and mHHS, respectively (AUC): 93.5 (0.79), 98.5 (0.84), 96.9 (0.81), and 85.9 (0.76).

CONCLUSIONS

Adolescents undergoing arthroscopic FAI surgery achieve clinically significant outcome improvement. We found that the vast majority of adolescents achieve MCID on hip-specific patient-reported outcome tools. However, although adolescents readily achieve MCID, a considerable improvement in postoperative outcome score is often needed to perceive a substantial benefit (SCB). The available hip outcome tools may be subject to ceiling effects for measuring clinically significant outcome improvement in adolescents.

LEVEL OF EVIDENCE

Level IV, case series.

The Intra-articular "Wave Sign" as a Landmark for Suture Anchor Placement in Arthroscopic Remplissage

In arthroscopic remplissage, surgeons may inadvertently pass sutures through the teres minor rather than the infraspinatus tendon. This misplacement of the sutures may lead to poor outcomes. The authors describe the novel use of the posterior band of the inferior glenohumeral ligament, known as the "wave sign," as a reliable intra-articular landmark for suture anchor placement to improve suture passage accuracy. Twelve cadaveric shoulders underwent arthroscopic remplissage by a fellowship-trained surgeon. During the first phase of the study, remplissage was performed on 6 specimens with standard technique. The intra-articular wave sign was visualized on all specimens. Specimens were dissected to the level of the joint, and the location of each suture anchor and suture pass was noted. Using the results from the first set of specimens, the surgeon performed remplissage in the second set of 6 specimens using specific measurements from intra-articular landmarks. On dissection of the initial 6 specimens, 75% of sutures were passed through the infraspinatus and 25% were passed through the teres minor. For the remaining 6 specimens, care was taken to place 1 suture anchor at the superior edge of the wave sign and 1 suture anchor 1 cm superior to the wave sign. When suture anchors were successfully passed above the superior tip of the wave sign, the likelihood of infraspinatus tendon penetration was 17 times greater. Placement of the suture anchors at or above the superior tip of the intra-articular wave sign most reliably produced capsulotenodesis of the infraspinatus muscle. [Orthopedics. 2017; 40(5):e831-e835.].

The "Safe Zone" Technique Improves Suture Placement and Accuracy During Arthroscopic Remplissage

In response to recent concerns about the accuracy of suture passage during arthroscopic remplissage, this study was conducted to determine whether a previously described "safe zone" technique can improve the accuracy of suture passage. A recommended safe zone technique was used for arthroscopic remplissage on 6 cadaveric specimens. The safe zone was described as a region at least 1 cm lateral and no greater than 3 cm distal to the posterolateral acromion. Results were compared with a control group of 6 specimens for which the safe zone technique was not used. For each group, 24 suture passes were performed. In the safe zone group, 83.3% (20 of 24) of sutures passed through the infraspinatus tendon. This was a significant improvement compared with the control group, in which only 25% (6 of 24) of sutures pierced the infraspinatus tendon (P<.01). In the safe zone group, 4.2% (1 of 24) of attempted suture passes were placed through the muscle or musculotendinous junction compared with 75% (18 of 24) in the control group (P<.01). Prevention of overmedialization improved significantly with the safe zone technique. In the safe zone group, both anchors had significantly more lateral (6 to 10 mm) suture passage compared with the control group (P<.01). The safe zone technique also showed greater precision of suture passes, and overall precision (SD) improved in 75% of passes. The safe zone technique significantly improved the accuracy of suture penetration into the infraspinatus tendon during arthroscopic remplissage. This reproducible method may help to prevent the reported complications of remplissage. [Orthopedics. 2017; 40(4):e598-e603.].

Efficacy of Celecoxib for Early Postoperative Pain Management in Hip Arthroscopy: A Prospective Randomized Placebo-Controlled Study

PURPOSE

To determine whether 400 mg of celecoxib administered 1 hour before hip arthroscopy surgery would reduce pain, provide reduction in overall narcotic consumption, and lead to more rapid discharge from recovery rooms.

METHODS

Ninety-eight patients were randomized to either the celecoxib group (n = 50) or the placebo group (n = 48). An a priori power analysis was done set to detect a difference of 0.50 on the visual analog scale (VAS), based on the senior author's preference. The number of patients planned for recruitment was rounded up to 100 to allow for flexibility in the study. Inclusion criteria were any patient at least 18 years old who underwent hip arthroscopy surgery performed by the senior author. All patients had less than Tönnis grade 2 arthritis. Exclusion criteria were allergy to sulfa-based drugs, prior adverse reaction to celecoxib, or patients who were on chronic narcotics for whom alternative pain management regimens were arranged before surgery. Randomization was performed on a 1:1 basis in blocks of 10 using sealed envelopes stating celecoxib or placebo. One hour before surgery, all patients received either 400 mg celecoxib or placebo. Patients were evaluated using a VAS preoperatively, immediately postoperatively, and at 1 and 2 hours postoperatively. Time from the operating room to "ready for discharge" and number of morphine equivalents of narcotic medication required in the postanesthesia care unit were recorded.

RESULTS

Age and preoperative VAS were similar between the celecoxib and placebo control group, with average ages of 34.2 ± 11.9 and 35.8 ± 11.6 (P = .27) and preoperative VAS of 2.1 ± 2.06 and 2.3 ± 1.98 (P = .29), respectively. The celecoxib group had 26 females and 24 males, whereas the placebo group had 29 females and 19 males (P = .42). The most common surgical procedures were labral repair (31 patients in the celecoxib group and 29 patients in the placebo group), and labral repair with acetabular osteoplasty (13 patients in the celecoxib group and 11 patients in the placebo group). There were no significant differences in procedures performed between the 2 groups (P > .05). At 1 hour postoperatively, patients who received celecoxib had a lower pain score that was statistically significant compared with the placebo group (4.6 vs 5.4, P = .03). There was a significant difference in discharge time between patients who received celecoxib and the control group (152.9 minutes vs 172.9 minutes, P = .04). There was no significant difference found in morphine equivalents consumed in the postanesthesia care unit between the 2 groups (15.3 vs 15.4, P = .48).

CONCLUSIONS

A preoperative dose of 400 mg of celecoxib led to statistically significantly reduced patient-reported pain on the VAS in the acute postoperative period after hip arthroscopy surgery, though the difference is not likely clinically significant. There was a significantly shorter time to discharge in patients who received celecoxib versus placebo.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.