Background: The use of the interference screw (IFS) for the cortical fixation of tendon grafts in knee ligament reconstruction may lead to converging tunnels in the multiligament reconstruction setting. It is unknown whether alternative techniques using modern suture anchor (SA) or bone staple (BS) fixation provide sufficient primary stability. Purpose: To assess the primary stability of cortical fixation of tendon grafts for medial collateral ligament (MCL) reconstruction using modern SA and BS methods in comparison with IFS fixation. Study Design: Controlled laboratory study. Methods: Cortical tendon graft fixation was performed in a porcine knee model at the tibial insertion area of the MCL using 3 different techniques: IFS (n = 10), SA (n = 10), and BS (n = 10). Specimens were mounted in a materials testing machine, and cyclic loading for 1000 cycles at up to 100 N was applied to the tendon graft, followed by load-to-failure testing. Statistical analysis was performed using 1-way analysis of variance. Results: There were no statistical differences in elongation during cyclic loading or peak failure load during load-to-failure testing between BS (mean ± standard deviation: 3.4 ± 1.0 mm and 376 ± 120 N, respectively) and IFS fixation (3.9 ± 1.2 mm and 313 ± 99.5 N, respectively). SA fixation was found to have significantly more elongation during cyclic loading (6.4 ± 0.9 mm; P < .0001) compared with BS and IFS fixation and lower peak failure load during ultimate failure testing (228 ± 49.0 N; P < .01) compared with BS fixation. Conclusion: BS and IFS fixation provided comparable primary stability in the cortical fixation of tendon grafts in MCL reconstruction, whereas a single SA fixation led to increased elongation with physiologic loads. However, load to failure of all 3 fixation techniques exceeded the loads expected to occur in the native MCL. Clinical Relevance: The use of BS as a reliable alternative to IFS fixation for peripheral ligament reconstruction in knee surgery can help to avoid the conflict of converging tunnels.

Background: The promising biomechanical stability of bone staples (BSs) in cortical fixation of tendon grafts for medial collateral ligament (MCL) reconstruction has been revealed by a previous investigation. However, it is currently unknown if the biomechanical stability of cortical fixation of tendon grafts depends on the BS design. Purpose: To assess the biomechanical stability of cortical fixation of tendon grafts in knee surgery using 4 different BS designs. Study Design: Controlled laboratory study. Methods: Cortical fixation of tendon grafts was performed in a porcine knee model at the tibial insertion area of the MCL using 4 different BS designs (n = 40): 8-mm width without spikes (n = 10), 8-mm width with spikes (n = 10), 14-mm width with spikes (n = 10), and 13 mm–wide 4-prong staples with spikes (n = 10). Specimens were mounted in a materials testing machine, and cyclic loading was applied to the tendon graft (500 cycles at 50 and 100 N, respectively), followed by load-to-failure testing. The Kruskal-Wallis test was performed for statistical analysis ( P < .05), and the post hoc Dunn test was performed for multiple comparisons. Results: In 4 of 10 specimens with graft fixation using BSs without spikes, slippage of the tendon underneath the BS led to failure of the construct during cyclic loading to 100 N. In the other groups, no fixation failure was observed during cyclic loading. Furthermore, graft fixation using BSs without spikes was found to have significantly more elongation during cyclic loading (8.2 ± 1.9 mm) and a lower ultimate failure load (170 ± 120 N) compared with graft fixation using narrow BSs with spikes (3.4 ± 1.2 mm [ P < .0001] and 364 ± 85 N [ P < .05], respectively) and graft fixation using broad BSs with spikes (4.5 ± 1.4 mm [ P < .05] and 429 ± 67 N [ P < .001], respectively). No statistical differences in elongation during cyclic loading or ultimate failure load were found between 4-prong staples with spikes (5.0 ± 1.3 mm and 304 ± 85 N) and narrow or broad staples with spikes. Conclusion: The biomechanical stability of cortical fixation of an MCL graft was comparable between each BS design with spikes (narrow, broad, and 4-prong) in a porcine knee model, whereas BSs without spikes led to failure of the fixation construct during cyclic loading in 4 of 10 specimens and increased elongation and lower ultimate failure loads in the remainder of the group. BSs without spikes may therefore not be recommended for graft fixation. Clinical Relevance: The use of BSs can help to avoid the conflict of converging tunnels in multiligament reconstruction surgery. An implant design with spikes yields significantly higher biomechanical stability than BSs without spikes.

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ZusammenfassungIn der Orthopädie und Unfallchirurgie hat die Bedeutung von PROMs („patient-reported outcome measures“) nicht nur klinisch und akademisch, sondern auch gesundheitspolitisch enorm zugenommen. Am Schultergelenk existieren zahlreiche solcher Messinstrumente, sodass für den Vergleich in Wissenschaft und Klinik eine einheitliche Verwendung geeigneter PROMs zu empfehlen ist. Ein PROM sollte wissenschaftliche Kriterien (u. a. Reliabilität, Validität, Responsiveness) erfüllen sowie in der jeweiligen Landessprache und nicht nur für die jeweilige Pathologie validiert sein. Zudem sollten Daten zur „minimal clinically important difference“ (MCID) vorliegen, um Ergebnisse nicht nur hinsichtlich ihrer statistischen Signifikanz, sondern auch der klinischen Relevanz beurteilen zu können. Ziel dieser Arbeit war es, für relevante Pathologien des Schultergelenks jeweils einen PROM zu empfehlen, der die o. g. Kriterien am besten erfüllt. Für das Schultergelenk werden dabei vom Research-Komitee der AGA unter Berücksichtigung dieser Kriterien folgende PROMs empfohlen: Constant-Murley-Score (CMS) für die Omarthrose bzw. Schulterendoprothetik, Western Ontario Stability Index (WOSI) für glenohumerale Instabilitäten und Western Ontario Rotator Cuff Index (WORCI) für Pathologien des Subakromialraums bzw. von Rotatorenmanschettenläsionen. Der Nottingham Clavicle Score (NCS) stellt ein geeignetes Instrument für die Klavikula sowie die angrenzenden Gelenke (Akromioklavikular- und Sternoklavikulargelenk) dar. Diese empfohlenen PROMs decken eine große Bandbreite an Schulterpathologien ab, sind bzgl. obiger Kriterien qualitativ hochwertig und für die deutsche Sprache validiert.

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