The Human Knee: Gross, Microscopic, Surgical, and Radiological Anatomy

Abstract

During the last years imaging techniques have rapidly developed in anatomy since they were included in the study of the human body. Normal patterns have been revisited and lately, in the era of evidence-based medicine, anatomy has shifted towards evidence-based morphology. Endoscopic and minimally invasive techniques require a different view and a better understanding of anatomy. Individualized patient care requires understanding of the individualized anatomy especially with regard to surgery. Anatomy is more well timed than ever and the papers selected for this special issue reflect the modern era of anatomy. The papers included are descriptive studies aiming to describe anatomy but they somehow represent different study designs and all of them have been conducted under a clinically orientated perspective. Although the human knee has been extensively studied, it seems that there are still research questions that need to be addressed. We would like to thank the authors for their contributions to this special issue. The fundamental work of all the reviewers is also acknowledged. In the paper "The 'oblique popliteal ligament:' a macro-and microanalysis to determine if it is a ligament or a tendon" B. Benninger and T. Delamarter challenge a well-known structure, the oblique popliteal ligament (OPL). Based on their observations the authors suggest that the OPL is indigenous to the distal semimembranosus muscle tendon unit. The microanalysis using an immunohistochemistry stain with PGP9.5 revealed a positive result for neuronal axons within both the semimembranosus tendon and OPL. Further microanalysis using an immunohistochemistry stain with β-tubulin revealed a positive stain for neuronal axons in the semimembranosus tendon, OPL, and lateral collateral ligament. Though the latter result leads the authors to question the validity of differentiating the tendon from ligament using this particular immunohistochemistry stain, the macroanalysis results are overwhelming, and the micro-analysis reveals striking similarities in the histology of both the OPL and semimembranosus tendon. In the paper entitled "The patellar arterial supply via the infrapatellar fat pad (of Hoffa): a combined anatomical and angiographical analysis" G. Nemschak and M. L. Pretterk-lieber describe the rich patellar arterial supply provided via the infrapatellar fat pad (of Hoffa). Five human patellae, one was dissected under the operation microscope, a second was made translucent by Sihlers-solution, and three underwent angiography using a 3D X-ray unit, were studied. The results revealed that the patella to a considerable amount is supplied by arteries coursing through the surrounding parts of the infrapatellar fat pad. The latter were found to branch off from the medial and lateral superior and inferior genicular arteries. Within the infrapatellar fat pad, these arteries formed a dense network of anastomoses which are all contributing to the viability of the patellar bone. The authors conclude that due to the rich arterial supply reaching the patella via the infrapatellar fat pad, it seems advisable to