Long-term Outcome of Total Knee Replacement: Does Obesity Matter?

Background: Although arthritic complications are common in the obese, many surgeons are reluctant to perform joint replacements in this population. We compared outcomes of total knee arthroplasties (TKAs) in normal weight and obese patients. Methods: 30 TKAs in 21 obese patients with BMI 30-49 (Group A – mainly mildly and moderately obese) were compared to a matched group of 53 TKAs in 41 non-obese patients with BMI 16-29.9 (Group B). Outcome measures included the Knee Society Score (a composite of clinical and functional parameters), radiographic results, and the need for revision or reoperation. Results: Median follow-up was 11.3 years; no patients were lost to follow-up during this time. The Knee Society Score rose 92 points in Group A to a final score of 184, and 95 points in Group B to a score of 193. There was no statistical difference in Groups A and B between the improvement in scores or the final score achieved. Osteolysis rates were not significantly different between the 2 groups (5% vs 13%), nor were radiolucency rates (0% vs 9.7%). Median alignment was also similar in both groups (8.1° vs 8.0° valgus). 13.3% of Group A required reoperation while none required revision, and 13.2% of Group B required reoperation with 3.8% requiring revision. Survival rates were similar in both groups (71.4% vs 61.5%). Conclusions: Moderate obesity does not affect the clinical and radiologic outcome of TKA. However, TKA results in improved mobility, enhancing the success of subsequent weight loss therapy.     

Primary Total Knee Replacement: Is Suction a Portal of Infection?

INTRODUCTION

Pulsed lavage during a total knee replacement usually leaves a pool of fluid on the surgical drapes. It is common practice to suck away this fluid using the same suction device used intra-operatively. This could be a cause of direct wound contamination. We hypothesised that bacteria contaminate fluid that collects around the foot in total knee replacement surgery and that suction equipment could be a portal of contamination. We also hypothesised that bacterial count in the fluid is lower if chlorhexidine, rather than saline, is used in the pulsed lavage.

PATIENTS AND METHODS

Forty patients undergoing primary total knee replacement were divided into two groups. The first group had pulsed lavage with normal saline and the second with 0.05% chlorhexidine.

RESULTS

At the end of the operation, 20 ml of fluid, pooled on the surgical drapes was aspirated and cultured for bacterial growth. None of the fluid samples showed bacterial growth.

CONCLUSIONS

Suction device used peri-operatively during knee replacement is unlikely to be a cause of wound contamination. Pulsed lavage with normal saline is as effective as lavage with chlorhexidine.     

Online Patient Ratings Are Not Correlated with Total Knee Replacement Surgeon–Specific Outcomes

Background

Despite potential concerns regarding their validity, physician-rating websites continue to grow in number and utilization and feature prominently on major search engines, potentially affecting patient decision-making regarding physician selection.

Questions/Purposes

We sought to determine whether patient ratings on public physician-rating websites correlate with surgeon-specific outcomes for high-volume total knee replacement (TKR) surgeons in New York State (NYS) from 2010 to 2012.

Methods

Online patient ratings were compared to surgeon-specific outcomes from the Statewide Planning and Research Cooperative System (SPARCS) database from the NYS Department of Health. For each surgeon, we determined the infection rate, re-admission rate, and revision surgery rate within the study period, as well as the mean inpatient length of stay, for TKR from the SPARCS database. Online ratings were collected from two physician-rating websites (Vitals.com and HealthGrades.com).

Results

One hundred seventy-four high-volume TKR surgeons were identified in NYS from 2010 to 2012. The mean rates of in-hospital infection, 90-day infection, 30-day re-admission, 90-day re-admission, and revision surgery were 0.25, 1.00, 4.89, 8.43, and 1.31%, respectively. The mean number of ratings for individual surgeons on HealthGrades.com and Vitals.com were 24.0 (range: 0 to 109) and 19.3 (range: 0 to 114), respectively, and mean overall ratings were 4.2 and 4.1 (out of 5) stars, respectively. As with online patient ratings of individual surgeons, variability was observed in the total adverse event rate distribution for individual surgeons. Despite sufficient variability in both online patient rating and surgeon-specific outcomes for high-volume TKR surgeons in NYS, no correlation was observed.

Conclusion

There was no correlation between surgeon-specific TKR outcome measures and online patient ratings. We therefore advise that patients exert caution when interpreting ratings on these websites.

     

Bicruciate-retaining Total Knee Replacement Provides Satisfactory Function and Implant Survivorship at 23?Years

Background

One of the goals of a TKA is to approximate the function of a normal knee. Preserving the natural ligaments might provide a method of restoring close to normal function. Sacrifice of the ACL is common and practical during a TKA. However, this ligament is functional in more than 60% of patients undergoing a TKA and kinematic studies support the concept of bicruciate-retaining (that is, ACL-preserving) TKA; however, relatively few studies have evaluated patients treated with bicruciate-retaining TKA implants.

Questions/purposes

I asked: (1) what is the long-term (minimum 20-year) survivorship, (2) what are the functional results, and (3) what are the reasons for revision of bicruciate-retaining knee arthroplasty prostheses?

Methods

From January 1989 to September 1992, I performed 639 total knee replacements in 537 patients. Of these, 489 were performed in 390 patients using a bicruciate-retaining, minimally constrained device. During the period in question, this knee prosthesis was used for all patients observed intraoperatively to have an intact, functional ACL with between 15° varus and 15° valgus joint deformity. There were 234 women and 156 men with a mean age at surgery of 65 years (range, 42–84 years) and a primary diagnosis of osteoarthritis in 89%. The patella was resurfaced in all knees. The mean followup was 23 years (range, 20–24 years). At the time of this review, 199 (51%) patients had died and 31 (8%) patients were lost to followup, leaving 160 (41%) patients (214 knees) available for review. Component survivorship was determined by competing-risks analysis and Kaplan Meier survivorship analysis with revision for any reason as the primary endpoint. Patients were evaluated every 2 years to assess ROM, joint laxity, knee stability, and to determine American Knee Society scores.

Results

The Kaplan-Meier survivorship was 89% (95% CI, 82%–93%) at 23 years with revision for any reason as the endpoint. Competing-risks survivorship was 94% (95% CI, 91%%–96 %) at 23 years. At followup, the mean age of the patients was 84 years (range, 63–101 years), the mean flexion was 117° (range, 90°–130°), the mean American Knee Society score improved from a preoperative mean of 42 (range, 26–49) to 91 (range, 61–100; p < .001). Twenty-two knees in 21 patients (5.6%) were revised, most commonly because of polyethylene wear.

Conclusions

ACL sacrifice may be an unnecessary concession during TKA. This study found satisfactory survivorship and function after more than 20 years of use for patients receiving a bicruciate-retaining TKA implant. A TKA that preserves cruciate ligaments provides a stable, well-functioning knee with a low likelihood of revision at long-term followup. Retaining both cruciate ligaments during knee arthroplasty is an attractive concept that is worth considering.

Level of Evidence

Level IV, therapeutic study.     

Does High Tibial Osteotomy Affect the Success or Survival of a Total Knee Replacement?

Background  

Whether a previous high tibial osteotomy (HTO) influences the long-term function or survival of a total knee arthroplasty (TKA) is controversial.     

Is Rapid Recovery Hip and Knee Replacement Possible and Safe in the Octogenarian Patient?

Background

Rapid recovery programs are now aimed to reduce costs of hip and knee arthroplasties by discharging patients directly home, shortening hospital length of stay (LOS), and reducing readmission rates. Although patients aged 80 years and older are included in the Medicare bundle, little work has been performed to determine if older patients can safely participate in rapid recovery programs.

Is Obesity a Contraindication for Minimal Invasive Total Knee Replacement? A Prospective Randomized Control Trial

Background  

Although total knee replacement (TKR) has been proven a very successful treatment modality for the end-stage knee osteoarthritis (OA) in obese patients, the rehabilitation period often is long and painful. Minimal invasive surgery (MIS) has gained much attention in TKR promising fast and less painful recovery. However, little is known about the effectiveness of the technique in the obese adult population.     

Does the Method of Component Fixation Influence Clinical Outcomes After Total Knee Replacement? A Systematic Literature Review

A systematic literature review was conducted to identify the best available evidence describing the differences in clinical outcome associated with the different methods of total knee replacement (TKR) fixation. Randomized trials published between 1980 and January 2011 comparing differences in clinical outcome scores between groups allocated to either cemented or uncemented fixation for TKR were included. Nine of the 11 studies included in the review reported no significant differences in clinical outcomes between groups with either cemented or uncemented prosthesis components. Critical appraisal of methodological bias revealed consistent shortcomings in study design and execution. It is apparent that more rigorous studies with longer follow-up periods are required to verify which method of fixation may be preferable in enhancing clinical outcomes.     

Does Interlimb Knee Symmetry Exist After Unicompartmental Knee Arthroplasty?

Background

Unicompartmental knee arthroplasty (UKA) has long been a treatment option for patients with disease limited primarily to one compartment with small, correctable deformities. However, some surgeons presume that normal kinematics of a lateral compartment UKA are difficult to achieve. Furthermore, it is unclear whether UKA restores normal knee kinematics and interlimb symmetry.

Questions/purposes

We determined knee kinematics exhibited during stair ascent by patients with medial- (MED-UKA) or lateral-UKA (LAT-UKA) and if the knee kinematics of the operated and nonoperated limbs were symmetrical.

Methods

Participants were 17 individuals with MED-UKA and nine with LAT-UKA, all with nondiseased contralateral limbs. For each limb, participants walked up four stairs for five trials while a motion-capture system obtained reflective marker locations. Temporal events were determined by force platform signals. Interlimb symmetry was classified for temporal gait and knee angular kinematics by comparing observed interlimb differences with clinically meaningful differences set at 5% of stride time for temporal variables and 5° for angular variables. The minimum postoperative followup was 6 months (median, 24 months; range, 6–53 months).

Results

Neither group demonstrated clinically meaningful mean interlimb differences. However, approximately half of participants of each UKA group displayed asymmetry favoring the operative or nonoperative limb with similar frequency.

Conclusions

Many patients undergoing UKA demonstrate kinematic interlimb symmetry during stair ascent. Interlimb asymmetry may be affected by a variety of factors unrelated to the UKA.

Clinical Relevance

A MED- or LAT-UKA can potentially restore normal knee function for a demanding task of daily life.     

Should We Use Intra-articular Tranexamic Acid Before or After Capsular Closure During Total Knee Replacement? A Study of 100 Knees

BackgroundIntraarticular (IA) administration of tranexamic acid (TXA) is a proven way of reducing blood loss in total knee replacement (TKR). However, different methods of administration have been described in literature such as placement of an intra-articular swab soaked in TXA before capsular closure or injecting TXA intraarticularly after capsular closure. We decided to compare these two methods.Materials and MethodsOne hundred consecutive patients planned for unilateral TKR between December 2018 and March 2019 were selected for the study and divided into 2 groups of 50 patients each. All patients received IV and oral TXA identically—15 mg/kg TXA IV preoperatively, 10 mg/kg IV TXA at 3 and 6 h postoperatively, and 1 g oral TXA for the next 2 days. Group A was given IA TXA via swab soaked with 1 g TXA in 100 ml normal saline (NS) before closure of arthtrotomy, while Group B was given 1 g of IA TXA via injection in the knee after capsular closure. Preoperative haemoglobin (Hb) and postoperative day 4 Hb values were measured. Blood loss was calculated and compared in both groups using Mann Whitney test.ResultThe mean blood loss was 652.23 ± 64.36 ml in Group A and 542.68 ± 266.23 ml in Group B. The difference in blood loss between both groups was found to be clinically significant with a p-value of 0.03236 (significant, p < 0.05).ConclusionInjecting TXA intraarticularly after capsular closure is more effective than using an intra-articular swab containing TXA.Level of EvidenceLevel III Retrospective Comparative study.     

Aggravation of Ankle Varus Incongruency Following Total Knee Replacement Correcting ≥10° of Genu Varum Deformity: A Radiographic Assessment

BackgroundThis study aimed to investigate the change in ankle varus incongruencies following total knee replacement (TKR) in patients with preoperative genu varum deformity of ≥10°.MethodsThe study cohort was composed of patients who underwent TKR in a single institution for knee osteoarthritis with preoperative genu varum deformity of ≥10° and concomitant varus ankle incongruencies. Eight radiographic measurements were evaluated preoperatively and postoperatively: mechanical tibiofemoral angle, mechanical lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle, tibial plafond inclination, talar inclination, tibiotalar tilt angle (TTTA), and tibia-mechanical axis angle. Of these, TTTA represented the quantitative degree of ankle joint incongruency.ResultsA total of 110 patients (male = 2; female = 108) were included in the analysis. The mean patient age was 68.9 (standard deviation [SD] 7.2) years at the time of TKR. All radiographic measurements showed significant changes postoperatively, representing the appropriate correction of genu varum deformity and restoration of the mechanical axis. Nineteen patients (17.3%) showed postoperative decrease in TTTA, 2 (1.8%) remained the same, and 89 (80.9%) showed increase. Overall, mean preoperative and postoperative TTTA were 3.3° (SD 2.2°) and 4.7° (SD 2.9°), respectively (P < .001), representing the aggravation of varus ankle incongruencies.ConclusionVarus ankle incongruencies showed aggravation following TKR despite correction of genu varum deformity and restoration of the mechanical axis. This could be an important cause of postoperative increase or development of ankle pain following TKR. Therefore, patients with preoperative varus ankle incongruencies need to be warned of possible aggravation of ankle symptoms and be evaluated before TKR.Level of EvidencePrognostic level III.     

Can Total Knee Arthroplasty Be Safely Performed Among Nonagenarians? An Evaluation of Morbidity and Mortality Within a Total Joint Replacement Registry

As the nonagenarian patient population continues to grow, more patients aged 90 and over will become candidates for total knee arthroplasty (TKA). This study evaluated the patient characteristics and incidence of postoperative morbidity and mortality of 216 nonagenarian TKA patients among 81,835 primary TKA patients followed by a total joint replacement registry. Nonagenarians had a greater number of comorbidities preoperatively, experienced a higher rate of deep vein thrombosis and 30 day mortality, and had a longer hospital length of stay. However, nonagenarians did not have an increased risk of infection nor pulmonary embolism and postoperative mortality was within expected rates for individuals 90 years and older. Higher readmission rates, however, highlight the benefits of close follow up during a prolonged postoperative period.     

Does Total Knee Arthroplasty Change Frontal Plane Knee Biomechanics During Gait?

Background  

Dynamic knee varus angle and adduction moments have been reported to be reduced after TKA. However, it is unclear whether this reduction is maintained long term.     

Knee manipulation for reduced flexion after Total Knee Arthroplasty. Is timing critical?

Background

Reduced flexion following knee arthroplasty (TKA) may compromise patient’s function and outcome. The timing of manipulation under anaesthesia (MUA) has been controversial. We present our experience in a high volume practice and analyse the impact of timing.

Does Greater Knee Flexion Increase Patient Function and Satisfaction After Total Knee Arthroplasty?

The purpose of this study was to determine whether high flexion leads to improved benefits in patient satisfaction, perception, and function after total knee arthroplasty (TKA). Data were collected on 122 primary TKAs. Patients completed a Total Knee Function Questionnaire. Knees were classified as low (≤110°), mid (111°-130°), or high flexion (>130°). Correlation between knee flexion and satisfaction was not statistically significant. Increased knee flexion had a significant positive association with achievement of expectations, restoration of a “normal” knee, and functional improvement. In conclusion, although the degree of postoperative knee flexion did not affect patient satisfaction, it did influence fulfillment of expectations, functional ability, and knee perception. This suggests that increased knee flexion, particularly more than 130°, may lead to improved outcomes after TKA.     

Can Original Knee Society Scores Be Used to Estimate New 2011 Knee Society Scores?

Background

The Knee Society Score (KSS) instrument is one of the most commonly reported primary outcome measures for total knee arthroplasty (TKA). Originally developed in 1989, the KSS was expanded and updated in 2011; however, the original KSS does not directly translate into the 2011 KSS. To date, no conversion algorithm has been developed, hindering the ability of researchers to adopt the 2011 KSS while maintaining their historical/longitudinal original KSS data.

Questions/purposes

The purpose of this study is to develop regression equations to map the original KSS to the 2011 KSS, allowing original and 2011 KSS data sets to be combined.

Methods

In this multicenter, nonrandomized study, a convenience sample of 815 patients undergoing primary TKA completed the original KSS questionnaire and the 2011 KSS questionnaire. Additionally, patient gender, patient age, and patient ethnicity were recorded. These data were then used to generate regression models to estimate the 2011 objective and function KSS from the original KSS. Of the 815 study patients, 476 (58%) were female and 339 (42%) were male at an average age of 67 years (SD 9.4). Roughly half of patients were assessed preoperatively (430 of 815 [53%]) with the remaining patients assessed postoperatively (386 of 815 [47%]). The average followup for postoperative patients was 4.4 years (SD 3.5 years).

Results

We have created a spreadsheet that can be used by individuals with no statistical training to crosswalk the objective and function subscores from the original KSS to the 2011 KSS [Supplemental materials are available with the online version of CORR®.]. The predictive model very accurately estimated the 2011 objective score, on average, within 0.22 points on the 100-point 2011 objective KSS at the cohort or aggregate level. The objective model accurately estimated the 2011 objective KSS within 8.83 points, on average, of the actual 2011 objective KSS at the individual patient level. However, as a result of large outliers, 37% of the estimated 2011 objective KSS were greater than 10 points from the actual 2011 objective KSS. To illustrate, if you use the model to estimate the 2011 objective KSS on a cohort of 100 patients, a patient with an original objective KSS of 88 will have an estimated objective KSS between 79 and 97 points. On the other hand, if you calculate an average original objective KSS of 88 for all 100 patients, the estimated average 2011 objective KSS will be 88 for the group. The predictive model accurately estimated the 2011 function KSS within 0.14 points on the 1000-point 2011 function KSS at the cohort level. At the patient level, the 2011 function KSS was also estimated within 8.8 points of the actual 2011 function KSS. However, 43% of the estimated function scores were greater than 10 points of the actual 2011 function KSS.

Conclusions

Clinicians and researchers can input their original KSS with demographic data into these equations to estimate the 2011 KSS objective and function scores. The small prediction error of 0.22 points that we calculated indicates that these models can be used to estimate the 2011 objective and function KSS at the aggregated cohort level. Although the average error score was within 10 points at the individual patient level, there was a high percentage of large errors resulting from outliers in the data set. These outliers seemed to be related to patients with excellent range of motion who had substantial pain and limited function or patients who have poor range of motion with excellent function and little pain. This may be inherent with the KSS or with the study sample. Nevertheless, one must use caution when estimating at the patient level. Additionally, the accuracy of the prediction scores decreases if any of the demographic variables included in this study are not available.

     

Does Arthroscopic Knee Surgery Work?

A recent randomized trial from the Finnish Degenerative Meniscal Lesion Study Group was published in the New England Journal of Medicine and attempted to determine the efficacy of partial meniscectomy without osteoarthritis. Patients were randomized to either arthroscopic partial meniscectomy or sham surgery. The authors concluded that the clinical outcomes after arthroscopic partial meniscectomy were no better than those after the sham surgical procedure. However, there are several important limitations of this trial that make it difficult to generalize to the 700,000 arthroscopic partial meniscectomies performed in the United States each year. In this small sample of 146 patients, patients with traumatic meniscal tears and locking symptoms—those most likely to benefit from a partial meniscectomy—were excluded. In addition, although patients with radiographic arthritis were excluded, most of the patients in the study had degenerative changes at the time of arthroscopy. Therefore it is difficult to determine whether the patients were symptomatic from their chondral degeneration or their degenerative meniscal tear. In our opinion this study does not change the role of surgery in current clinical practice. The primary indication for arthroscopic partial meniscectomy remains symptoms of well-localized joint line pain with acute onset and mechanical symptoms such as catching or locking that have failed comprehensive nonoperative management.