Computer-assisted decision analysis in orthopedics: resurfacing the patella in total knee arthroplasty as an example

The evolution of patellofemoral prosthetic design in total knee arthroplasty: how far have we come?

Total knee arthroplasty (TKA) has evolved into a successful, cost-effective treatment for end-stage knee arthrosis.The patellofemoral articulation in TKA has largely been ignored during its development despite being an important determinant of outcome.New technologies still need further development to incorporate the patella in TKA surgical planning and operative technique.Alternative approaches to alignment in TKA will have a secondary impact on patellofemoral mechanics and possibly future implant designs.Technologies that assist with precise implant positioning may alter our understanding and overall practice of TKA. Cite this article: EFORT Open Rev 2019;4:503-512. DOI: 10.1302/2058-5241.4.180094.

Health in elite sports from a salutogenetic perspective: athletes' sense of coherence

OBJECTIVE

Considering the high number of stressors encountered in the context of elite sports, a high sense of coherence (SOC) is crucial to allow athletes to maintain their health from both short- and long-term perspectives. The aim of this cross-sectional study was to investigate SOC in a population of elite athletes, focusing on identification of subsets of athletes with particularly high and low SOC scores, and any related predictors. The elite athletes' SOC scores were also evaluated for differences with those of the general population of Germany; whether a correlation between SOC and subjective health existed was additionally examined.

METHOD

In total, 698 male and female elite athletes, drawn from Germany's highest-level national track and field squads, and first and second division handball teams, completed a survey that included the SOC-L9 Scale and measures of subjective health, sociodemographic information, and the number of injury lay-offs experienced during the athletes' careers to date.

RESULTS

Classification tree analysis reveals six contrast groups with varying SOC scores. Several interacting factors determine the group to which an athlete belongs. Together with overuse injuries, additional factors are age, gender, and completed/not completed apprenticeship/degree. Female athletes aged between 19 and 25, who had already been subject to lay-offs due to overuse injuries, comprise the group with the lowest SOC scores. Overall, the SOC of elite athletes is slightly lower than in the general population. In accordance with other studies, a stronger SOC is also correlated significantly with better global subjective health.

CONCLUSION

The identification of contrast groups with varying SOC scores contributes to the development of more targeted salutogenetic health promotion programs. Such programs would ideally include learning modules pertaining to coping with overuse injuries, as well as social support systems aiming to effectively combine education and elite sport.

Method for selection of femoral component in total knee arthroplasty (tka)

A method is proposed enabling a surgeon to preoperatively determine the preeminent type and size of prosthesis, from those available, to be used in a particular patient undergoing knee replacement surgery. Parameters of healthy knee geometry were estimated by employing an unsupervised neural network. These estimated parameters were then applied in a χ(2) goodness of fit (GoF) test to determine which femoral prosthesis type and size delivers the most appropriate fit. This approach was used to determine the most suitable match of three implants for 34 different cases. Implant C performed the best and was the optimal fit in 59% of the cases, Implant A was the best fit in 38% of the cases and Implant B the best fit in 3% of the cases. This method shows promise in aiding a surgeon to select the optimal prosthesis type and size from an array of different conventional total knee replacements.

Using observational data for decision analysis and economic analysis

In orthopaedic surgery, clinical decisions must often be made with imperfect information from observational studies and limited resources. Decision analysis and cost-effectiveness analysis have emerged as evidence-based tools to assist in making choices in situations in which uncertainty exists. This review demonstrates how decision-analysis and cost-effectiveness-analysis tools can be used to expand on published observational studies within the context of a specific clinical scenario. Critical evaluation of clinical and economic data is of increasing importance in today's health-care delivery climate. The use of decision analysis and cost-effectiveness analysis as tools to augment observational studies can assist clinicians, patients, and policy makers in choosing techniques that will optimize benefits. A clear understanding of and the ability to use and apply these tools will allow surgeons to participate effectively in health-policy decisions to enhance the overall quality and efficiency of care that is delivered.

To resurface or not to resurface the patella in total knee arthroplasty

The management of the patellar articular surface at the time of primary total knee arthroplasty (TKA) is controversial. We used expected-value decision analysis to determine whether the patella should be resurfaced in TKA, and also whether secondary resurfacing on an unresurfaced patella is worthwhile. Outcome probabilities and utility values were derived from randomized controlled trials only. A decision tree was constructed and fold-back analysis was performed to ascertain the best treatment path. Sensitivity analyses were performed to determine the effect on decision-making of varying outcome probabilities and utilities. Our model showed patellar resurfacing is the best management strategy for the patella at the time of primary TKA. This decision is robust to changes in the specific data: the best path would remain the same as long as the incidence of persistent anterior knee pain (AKP) with resurfacing remains less than 29% (current mean, 12%) or the incidence of AKP after nonresurfacing falls below 12% (current mean, 26%). Delayed (ie, secondary) patellar resurfacing for ongoing patellar pain provides inferior results for the majority of patients.

LEVEL OF EVIDENCE

Level II, decision analysis. See the Guidelines for Authors for a complete description of levels of evidence.

Once a cesarean always a cesarean? A computer-assisted decision analysis

OBJECTIVE

A previous decision analysis models for two strategic choices for trial of labor or repeated cesarean after prior cesarean concluded that the degree of wish for an additional future pregnancy appeared to be a major determinant for choice between the two strategic options. We had extended the analysis model to stillbirth and hypoxic-ischemic encephalopathy in addition to placental complications while updating most of the outcomes in the decision tree.

STUDY DESIGN

A model was formulated using a decision tree based on reported probabilities for various outcomes and estimated utilities. The question asked was should trial of labor or repeated cesarean be performed after a prior cesarean, with a varying desire for an additional pregnancy. The highest expected outcome determines the preference of our model.

RESULTS

Our model favors repeated elective cesarean (0.9947) over trial of labor (0.9917) after a previous cesarean and is the preferred approach. This approach was preferable irrespective of the probability of additional pregnancy.

CONCLUSION

In contrary to previous models, when taking into account the occurrence of a live infant birth, birth of an infant with hypoxic-ischemic encephalopathy stillbirth, neonatal death, abnormal placental implantation, hysterectomy and maternal death the preferred approach for women with previous cesarean is an elective repeated cesarean rather than trial of vaginal delivery.

Should we resurface the patella in total knee replacement? Experience with the Nex Gen prothesis

Patellar resurfacing is a controversial issue in primary total knee replacement. So, we took advantage of a large study to try and answer this question. An open prospective multicentric study was conducted about the outcome of the Nex Gen Total Knee prosthesis with clinical and radiological follow-up at regular intervals (1, 2 and 5 years). The data were centrally collected and analyzed by independent observers. A total of whole 5,915 cases were included (487 in the French group); incidences of patello-femoral pain were observed in both French and international groups and compared between cases with or without resurfaced patellae. Only osteoarthritic cases were selected for this particular study. Statistical analysis was performed using a Pearson's Chi-square test with a 95% confidence interval. The frequency of preoperative pain was significantly higher in the French group; 85.1% versus 66.6% (p<0.05). No patello-femoral pain appeared in preoperatively painless patients in the French group. The frequency of lateral patellar release was similar in both groups. 35.7% of the patellae were resurfaced in the international group versus 98.8% in the French one. At 2 years, patello-femoral pain was observed in 6.3% of cases in the former group versus 0.7% in the latter one. The risk of having patello-femoral pain was 9.45 times higher in the international group. When considering resurfaced cases in both groups the risk of having anterior knee pain was not significantly different (p=0.35). In the French group, one case out of nine (11.1%) with patello-femoral pain had not been resurfaced, while 129 cases out of 151 (85.4%) had not had a resurfacing in the international group. This emphasizes the effect of patellar implant on pain. Although patello-femoral pain is multifactorial, this analysis tool is powerful in getting rid of the "center effect " (cf Swedish register). Even if a longer follow-up for confirmation is needed, our data favor patellar resurfacing with this type of implant in spite of the fact that the trochlear design was considered as anatomical.

Decision analysis in orthopaedics

Orthopaedic surgeons are faced with an ever-growing amount of clinical information from which they are required to make treatment decisions. Many of these decisions can be approached with relative certainty. However, there are many situations where the optimal decision is less clear. These treatment decisions will have competing risks, benefits, or costs. Decision analysis is one method to critically evaluate alternative treatment options with multiple potential outcomes. This method of decision making can be extremely valuable because of the growing number of treatment alternatives, and to the ever-increasing complexity of medical scenarios.

Orthopaedic crossfire--All patellae should be resurfaced during primary total knee arthroplasty: in opposition

After more than 20 years of debate, the decision on whether to resurface the patella in primary total knee arthroplasty (TKA) remains controversial. Laboratory testing suggests that performing a TKA alters knee kinematics. Every study to date has suggested that kinematics are more abnormal when the patella is resurfaced than when it is retained. In addition, patellofemoral contact areas are higher and contact stresses are lower with the native patella compared with the resurfaced patella after TKA. Virtually every clinical study of bilateral knee arthroplasty in which one patella has been resurfaced and the other has not has shown either equivalent results or a preference for the unresurfaced side. Laboratory and clinical data indicate that not resurfacing the patellar is a viable if not preferable option in most TKA patients.

Health care economic analyses and value-based medicine

Health care economic analyses are becoming increasingly important in the evaluation of health care interventions, including many within ophthalmology. Encompassed with the realm of health care economic studies are cost-benefit analysis, cost-effectiveness analysis, cost-minimization analysis, and cost-utility analysis. Cost-utility analysis is the most sophisticated form of economic analysis and typically incorporates utility values. Utility values measure the preference for a health state and range from 0.0 (death) to 1.0 (perfect health). When the change in utility measures conferred by a health care intervention is multiplied by the duration of the benefit, the number of quality-adjusted life-years (QALYs) gained from the intervention is ascertained. This methodology incorporates both the improvement in quality of life and/or length of life, or the value, occurring as a result of the intervention. This improvement in value can then be amalgamated with discounted costs to yield expenditures per quality-adjusted life-year ($/QALY) gained. $/QALY gained is a measure that allows a comparison of the patient-perceived value of virtually all health care interventions for the dollars expended. A review of the literature on health care economic analyses, with particular emphasis on cost-utility analysis, is included in the present review. It is anticipated that cost-utility analysis will play a major role in health care within the coming decade.

Prophylactic pinning of the contralateral hip in slipped capital femoral epiphysis : evaluation of long-term outcome for the contralateral hip with use of decision analysis

BACKGROUND

The risk of a contralateral slip in patients who are first seen with a unilateral slipped capital femoral epiphysis has been reported to be 2335 times higher than the risk of an initial slip. The overall prevalence of bilaterality varies widely throughout the literature, with some reports indicating rates as high as 80%. This finding has led many authors to recommend prophylactic pinning of the contralateral asymptomatic hip in patients presenting with a unilateral slipped capital femoral epiphysis.

METHODS

A decision analysis model with probabilities for the occurrence of contralateral slip and for the severity of slip at different intervals of follow-up was used in the present study. These probabilities were compared with those for various outcomes when the contralateral hip is prophylactically pinned. Scores representing long-term outcome, according to the Iowa hip-rating system, were used in the model as a measure of utility. The probabilities of contralateral slip and the rates of slip severity were taken from large retrospective series. All meaningful clinical scenarios with regard to long-term outcome for the hip were considered in the model. Variables of uncertainty were subjected to sensitivity analyses in order to explore the effect on outcome over the range of plausible values for variables of interest.

RESULTS

The results showed a benefit in the long-term outcome for patients who had prophylactic pinning of the contralateral hip. The threshold level at which a benefit is obtained with prophylactic pinning is expressed according to the rates of sequential slip, rates of slips overlooked at follow-up, and complications associated with prophylactic pinning of the contralateral hip.

CONCLUSIONS

The decision model shows that, when pooled data are used to predict probabilities of sequential slip, treatment of the contralateral hip with prophylactic pinning is beneficial to the long-term outcome for that hip. When considering prophylactic pinning of the contralateral hip, the clinician should use sound clinical judgment with respect to the age, sex, and endocrine status of the patient. Long-term follow-up studies are needed to establish the efficacy of prophylactic pinning, but the predictions in the present study, which are based on findings in the literature, support the safety of this procedure.

Patella in total knee arthroplasty

The patella is a reliable guide to the success or failure of a total knee replacement. Patients who do not experience peripatellar symptoms or a patellar complication usually have a successful result. Conversely, peripatellar symptoms or complications usually reflect an underlying problem with surgical technique, component designs, or both. Current designs still do not replicate normal kinematics, and current instrumentation and techniques significantly alter the anatomy of the patellofemoral articulation in a substantial percentage of patients. Reproducing extensor mechanism balance and using components that provide adequate congruency and contact area through a physiologic arc of motion should lead to a successful result with minimal patellar symptoms or complications whether or not the patella is resurfaced. Attempting to achieve normal patellofemoral kinematics and minimize patellar complications has led to a better understanding of total knee arthroplasty.