Tendon Injuries

The study was approved by the local ethics committee.
According to the "guidelines for the process of cross-cultural adaptation of self-report measures" the VISA-A score was cross-culturally adapted into German (VISA-A-G) in six steps [17 (link)].
Step I: Initial translation from English to German (forward translation) was performed by three independent translators with German mother tongue. An orthopaedic surgeon specialised in foot, ankle, and Achilles tendon, and a sport scientist both were aware of the concepts being examined in the questionnaire. A third translator without medical background ("naïve translator") was not familiar with the questionnaire's concepts. Written reports were made to indicate rationales for decision making, linguistic difficulties and problems with regards to content.
Step II: Considering the original VISA-A the resulting three German versions were synthesized during a consensus meeting of the three translators. A written report documented the procedure.
Step III: Back translation of the preliminarily VISA-A-G questionnaire was then conducted by two American English native speakers fluid in German but without medical background and blind to the original VISA-A.
Step IV: An expert committee was constituted including forward and back translators, a health professional, and a language professional. This panel developed the prefinal VISA-A-G version by consensus discussion with respect to semantic, idiomatic, experiential, and conceptual equivalence based on all previous material (original, target and back translated questionnaires including the respective reports).
Step V (pretesting): The prefinal questionnaire was filled out by a cohort of 35 male and 42 female persons (asymptomatic persons). These persons were then asked regarding their individual understanding of the questionnaire's items. The interviewer prepared a report on the test subjects, understanding of the items, and their decision making. Again the questionnaire was adapted respectively resulting in a final version.
Step VI: The final version of the VISA-A-G questionnaire and all reports and forms were then subjected to a review done by the developers of the VISA-A-G questionnaire for appraisal of the adaptation process.
The final VISA-A-G questionnaire was then subjected to psychometric testing including an analysis of reliability and validity in 30 Achilles tendinopathy patients and 79 asymptomatic people. Internal consistency was evaluated in 30 Achilles tendinopathy patients.
This was done following closely the procedure described in the original VISA-A report [8 (link)].
Test subjects: For reliability and validity testing four groups of test subjects were defined according to the status of their Achilles tendon. Group I included 15 preoperative Achilles tendinopathy patients selected prospectively from the own center. Group II consisted of 15 Achilles tendinopathy patients conservatively treated. These patients were recruited from review of the most recent charts in our sports medicine center. 48 Frankfurt/Main university pharmacology students (one class preparing for their examinations) without Achilles tendon complaints constituted group III. Group IV was formed by 31 members of three local running clubs serving as non injured but active controls. That population was recruited by direct contact during their practise.
Inclusion criteria for all four groups were: age over 18 years, willingness to take part in this project, and ability to give written informed consent. Contrasting to the original VISA-A publication [8 (link)] only patients suffering from unilateral Achilles tendinopathy were included (group I and II). Achilles tendinopathy was defined as tenderness of the midportion of the Achilles tendon 2 to 7 cm proximal to the Achilles tendon insertion and a history of load induced pain in this area [2 (link)-4 (link)]. This clinical diagnosis includes degenerative Achilles tendon lesions, Achilles tendon partial tears on a microscopic level, and paratendinosis or combinations of these. For the control groups (group III and VI) subjects with previous Achilles tendon injuries were included, if they did not complain any actual symptoms or functional deficiencies. Persons with inadequate compliance and pregnant or nursing women were excluded from participating in any of the four groups. Patients (group I and II) with bilateral symptoms, subtotal or complete Achilles tendon tears, insertional Achilles tendinopathy, Haglund's disease, and relevant injuries or previous surgery of the lower extremity, radicular and pseudoradicular induced pain were excluded.
To document the individual level of activity the ankle activity score which is a reliable, valid, and sensitive measure [18 (link)] was calculated for all test subjects.
For concurrent validity testing all participants (n = 109) completed the VISA-A-G questionnaire and Achilles tendinopathy severity was additionally rated by an orthopaedic surgeon specialized in Achilles tendon disorders (HL) using a generic tendon grading system [19 (link)] and a "classification system for the effect of pain on athletic performance" [20 ]. Even if the clinimetric properties of these tools are not formally validated so far they have been used as a standard for concurrent validity testing in previous VISA-A validation research [8 (link),9 (link),12 (link)]. Percy and Conochie categorized pain and function following surgery of Achilles tendon tears: "Excellent" means full function and no residual disability. "Good" is defined as full function with no real limitation of activities and minor pain. A "fair" result is represented by some limitation of activities. Severe weakness and marked limping indicates a "poor" result [19 (link)]. Curwin and Stanish assessed six degrees of reported exercise induced tendon pain and the level of sports performance: 1 = no pain and unrestricted level of sports performance; 2 = pain only with extreme exertion and unrestricted level of sports performance; 3 = pain with extreme exertion and 1 to 2 hours afterward and normal or slightly decreased level of sports performance; 4 = pain during and after any vigorous activities and somewhat decreased level of sports performance; 5 = pain during activity forcing termination and markedly decreased level of sports performance; 6 = pain during daily activities and unable to perform sport [20 ].
Besides this, VISA-A-G results for patients expected to present moderate symptoms (group II) and patients probably suffering the most severe symptoms (group I) were compared with the controls (group III and IV).
Next, the VISA-A-G ratings from this study were compared with the respective VISA-A group values presented in the original publication [8 (link)].
For reliability testing a subset of subjects were included. For test retest reliability all conservative patients (n = 15), all students (n = 48), and all joggers (n = 31) were evaluated by the VISA-A-G questionnaire two times within one week. Intertester reliability was assessed by comparing the results when both authors administered the VISA-A-G questionnaire independently in a one to seven days interval to five participants from the students and conservative Achilles tendinopathy group respectively.

The biomechanical testing setup and the data acquisition protocol were adopted from our previous investigation^{31 (link)} evaluating repair techniques of type III FDP tendon avulsion injuries, seeming most suitable for the investigation of biomechanical characteristics of type IV injury repairs as well. To establish a firm hold of the specimens and to enable visualisation of the dynamics of the repair throughout biomechanical testing we used a distal phalanx (DP) holding cylinder mounted on an electromechanical tensile testing machine (Zwick Z050, ZwickRoell GmbH, Ulm, Germany) equipped with a 1 kN load cell. Prior to testing the load cell was checked for its accuracy in the low load region using calibrated weights. In the range from 0.1 to 5 N the maximum deviation was 7 mN. Following repair, each specimen was placed into the DP cylinder allowing full exposure of the repair through its semicircumferential window. Using common white plaster as a fixation material, all repair components remained unaffected, thus preventing unintended rotation or tilt of the specimen within the cylinder. A ball-joint linking the tensile testing machine to the cylinder ensured an optimal alignment of the specimen-repair construct along the longitudinal axis of the distal phalanx and the reattached tendon when strain was applied, preventing bias by translational forces to the repair site. Seven centimetres proximal to the repair, the tendon was retained using a standard tensile clamp. The articular line of the distal phalanx, of the avulsion fragment, as well as the tendon at the corresponding articular line level were marked with a blue felt tip pen under a baseline preload of 2 N allowing visual assessment of the repaired injury components (Fig. 4). Continuous cyclic loading from 2 to 15 N at a rate of 5 N/s for a total of 500 cycles simulated immediate postoperative mobilisation. Upon completion of cyclic loading, specimens were loaded to failure at a rate of 20 mm/min. A high-resolution camera placed in front of the experimental setup documented bony and tendinous gap formation at the repair site at the initial 2 N preload, periodically every 100 cycles, as well as, when loaded to failure, disclosing failure mechanisms. Consistent with methods used in our former studies^{30 (link),31 (link)} on FDP tendon avulsion repair, the load at first noteworthy displacement (2 mm) representing the load at the occurrence of an avulsion fragment- or reattached tendon derived, clinically relevant global system displacement was evaluated. To allow a thorough perception of the repair- and failure biomechanics, following data were recorded and analysed as well: load at failure, elongation of the system, gap formation at the bone–bone contact line (proximalisation of the fragment resulting in an articular step off), gap formation at the bone–tendon insertion line, and the mechanism of failure. Reaching a structural balance of the tendon and the suture material after 50 cycles, elongation of the system was measured between the 50th and the 500th cycle. Bony or tendinous dynamics at the repair site documented on photographs were analysed with Image J Software (National Institutes of Health, Washington, DC, United States).Figure 4

(A) Specimen preparation and injury simulation prior to repair. (B) Repaired specimen secured in the DP holding cylinder mounted on the tensile testing machine. Distance (r) indicating the 10 mm reference for further image evaluation.