Introduction

Clinical studies play a crucial role in assessing the effectiveness and safety of treatments in orthopedics and trauma surgery. For a long time, the focus of scientific follow-up on treatments for orthopedic conditions was primarily on objective outcomes (e.g., range of motion measurements), while in recent years, there has been an increasing emphasis on subjective parameters from the patient’s perspective. Consequently, numerous joint-specific measurement instruments (questionnaires, scores, or patient-reported outcome measures [PROMs]) have been developed.

To achieve meaningful and reliable scientific results, careful selection of appropriate questionnaires for data collection is of great importance. When selecting questionnaires for clinical studies, various aspects need to be considered. Above all, a version validated for the native language should be available, characterized by a clear and compact structure with a manageable number of questions to ensure high participation and a high response rate.

Moreover, questionnaires should meet scientific criteria established by the COSMIN (consensus-based standards for the selection of health measurement instruments) initiative [1], which are divided into three aspects:

  • Reliability: Indicates the precision and reliability of a measurement, i.e., whether the same value is obtained with repeated measurements, ensuring consistency. This includes internal consistency, i.e., whether individual measurement instruments within a questionnaire are consistent regarding the examined pathology.

  • Validity: Refers to the validity of a measurement, determining whether the correct aspect is measured, i.e., whether the desired pathology is comprehensively captured.

  • Responsiveness: Describes whether a questionnaire is capable of assessing changes in the patient’s condition over time or in response to a specific treatment.

Other crucial aspects of a PROM are the ceiling and the floor effects. This means that in a questionnaire, either an unusually high number of patients reach the lowest (floor) or the highest (ceiling) score, making it inadequate to measure relevant changes or differences in these populations at the respective extremes [2].

Furthermore, in the future, study results will increasingly be interpreted not only based on statistical measures such as the p-value but also within their clinical context. Two characteristics will gain more importance in this regard:

  • Minimal clinically important difference (MCID): Represents the smallest change in a score associated with a clinically significant (for the patient detectable) change for the patient, whether it is a difference between different populations or within a group at different timepoints [3].

  • Patient acceptable symptom state (PASS): Represents the score value at which the patient expresses wellbeing [4].

Improvement according to the MCID scale means “feeling better,” while achieving PASS means “feeling good.”

From the multitude of questionnaires used in orthopedics and trauma surgery in clinical studies, depending on the specific question and the particular body region, the following three particularly suitable questionnaires exemplify the aforementioned aspects:

Example scores

Knee

The IKDC-2000 (International Knee Documentation Committee Subjective Knee Form) covers three essential aspects through 18 questions: 1) knee-specific symptoms, 2) physical activity, and 3) functionality of the knee joint before and after an injury [5]. The questionnaire can be completed in about 10 min [6]. The IKDC-2000 is validated for various pathologies of the knee joint (ligamentous and meniscal injuries, patellofemoral pain syndrome, patellofemoral instability, knee osteoarthritis, cartilage damage). Scores can reach a maximum of 100 when a participant has no symptoms or limitations. Normative values have been collected from over 5000 knees and are categorized by different age groups and genders. A clinically relevant difference in the score for anterior cruciate ligament reconstruction, according to the MCID, is a difference of 9 points [4].

Shoulder

For a long time, there was a lack of valid shoulder scores for assessing the symptom of “instability,” until Kirkley et al. published the Western Ontario Shoulder Instability Index (WOSI) in 1998, a questionnaire specifically developed for glenohumeral instability [7]. It includes a total of 21 questions covering four categories (1. physical complaints, 2. sports, leisure, and work, 3. everyday life, and 4. emotion/life quality), with results ranging from 0 (best result) to 2100 points (worst result) [8]. The questionnaire has been assessed as reliable and valid, and a validated German-language version is available [9]. Furthermore, both the MCID (60.7 to 220 points) and PASS (620 points) for WOSI concerning glenohumeral joint instability have been determined in the literature [10].

General quality of life

The EQ-5D (EuroQol 5 Dimensions) is a questionnaire for assessing health-related quality of life. It measures general health in five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The calculated score ranges from −0.4 (worst score) to 1 (best score). It is used in various medical fields, including orthopedics and trauma surgery. For example, the MCID for assessing quality of life after knee arthroplasty is 0.15. The EQ-5D is applied for all pathologies and is considered the most common instrument for assessing quality of life. Country-, age-, and gender-specific norm values also exist [11].

The above examples illustrate that the mentioned selection criteria should be considered to choose suitable questionnaires for a clinical study. It may also be useful to combine multiple questionnaires to obtain a more comprehensive picture, but feasibility in clinical practice should be considered. In general, joint-/pathology-specific scores should be backed up by a quality of life and activity score. Recommendations regarding shoulder and knee scores are presented in Tables 1 and 2.

Table 1 Overview of recommendations for shoulder PROMs by the AGA Research Committee (modified from [8])
Full size table
Table 2 Overview of recommendations for knee PROMs by the AGA Research Committee (modified from [6])
Full size table

However, the choice of questionnaires in clinical studies is not an isolated process but always part of a comprehensive study design. The integration of objective clinical measurements and imaging techniques can complete the overall picture and strengthen the robustness of study results.

Conclusion

  • Study results should be collected using standardized questionnaires to simplify scientific communication and evaluation.

  • Each applied questionnaire should be validated for the investigated injury or condition and meet all scientific quality criteria regarding reliability, responsiveness, and ceiling or floor effects.

  • Regarding general quality of life, the EQ-5D (EuroQol 5 Dimensions) serves as an additional secondary outcome parameter.

  • Questionnaires should be manageable within a reasonable timeframe, with a minimal number of questions to achieve a high response rate.

  • Study results should be interpreted not only in terms of statistical significance but, most importantly, clinical relevance (minimal clinically important difference = MCID and patient acceptable symptom state = PASS).