362 Anatomy Applied to Medicine and Surgery. 



tial excision; or, the incision may start at the posterior 

 margin of one condyle and pass, in a convex manner, 

 across the front of the articulation, below the patella, 

 dividing the ligamentum patellae near its insertion, and 

 terminating at the posterior margin of the outer condyle. 

 The knee is now flexed, the patellar ligament and the an- 

 terior parts of the capsule, along with the patella, turned 

 up, the leg still more flexed, the lateral crucial ligaments 

 divided and the lower part of the femur excised. In con- 

 nection with this step, i.e., sawing the femur, the axes of 

 the two main bones of the leg must be borne in mind. The 

 two bones (femora), which are separated above by the 

 pelvic bones, approach the middle line, below, while the 

 tibiae, on which the femora rest, are vertical, and hence, 

 when the bones are sawn, it is necessary to preserve this 

 relationship, so that, for the femur, the saw should be ap- 

 plied, in the antero-posterior direction, at right angles to 

 the axis of the shaft, for, if this were not done, then the 

 tibia, uniting with the obliquely sawn femur, would be di- 

 rected so, that the foot would be much in front of or much 

 behind its normal position. Again, the saw should be ap- 

 plied so that the cut is, in the transverse direction, parallel 

 with the free surface of the condyles, for, were it not, 

 then the leg would point either inwards or outwards as the 

 case might be. The tibia is divided in a direction parallel 

 with its upper surface, i.e., at right angles to the shaft. 

 It must not be forgotten that the epiphyseal lines should 

 not be encroached upon, otherwise arrest of growth 

 would occur, and it may be roughly stated, that, in a child 

 of about eight years of age, half an inch of the femur may 

 be removed ; whereas, in a youth of seventeen years of 

 age, one inch is safe, without endangering the epiphyseal 

 line. In the tibia, as already stated, the lower margins of 

 the tuberosities mark the epiphyseal line and these mar- 



