The rupture of the cranial cruciate ligament is ↲ the most common cause of hind limb lameness in dogs. The m↲ ultifactorial etiopathogenesis is discussed in this manusc↲ ript. The causes include immunological and inflammatory fa↲ ctors, genetic components and the plastic deformation of t↲ he tibia – the latter resulting in altered biomechanics of↲ the stifle. Many therapeutic options have been developed ↲ depending on the suspected cause. Tibia osteotomies repres↲ ent the newest therapeutic approach to restore the physiol↲ ogical biomechanics of the stifle. The best known techniqu↲ es are certainly the tibial tuberosity advancement (TTA) a↲ nd the tibial plateau levelling osteotomy (TPLO). While th↲ e TTA results in a broader tibia, the TPLO results in a re↲ duced tibia plateau angle. In our study we examined the pr↲ oximal tibia of 100 dogs with intact cranial cruciate liga↲ ment (group I) and 100 dogs with ruptured cranial cruciate↲ ligament (group R). Tibia width and the tibial plateau an↲ gle (+/- standard deviation) were measured. The tibia widt↲ h was 39.43 +/- 9.13mm in group I, and 40.83 +/- 8.98mm in↲ group R. The tibia plateau angle of dogs in group I was 2↲ 7.20 +/- 3.39°, in group R 28.58 +/- 3.76° respectivley. L↲ ogisitc regresssion analysis indicated that the odds for a↲ rupture of the cruciate ligament increases by 34% per mil↲ limeter decrease of the tibia width and about 15% per degr↲ ee increase of the tibia plateau angle. Therefore our stud↲ y confirms that the odds for a rupture increases with a sm↲ all tibia width and a steep tibia plateau angle. This expl↲ ains the good outcome of both surgical techniques. Inadequ↲ ate breeding is the suspected cause for the plastic deform↲ ation of the proximal tibia.