Background: Total knee replacement remains one of the most common knee surgery practices worldwide. The operative procedure universally requires the use of cutting jigs to resect predetermined amounts of bone irrespective of the preoperative anatomy and morphology of the femur and tibia.

Aims: The aims of this study were to elucidate anatomical morphological differences between ethnicities pre-operatively and to assess whether any change elucidated was preserved post-operatively.

Method: This was a retrospective study comparing the pre and postoperative lateral view X-Rays of TKRs performed. Distances measured from most prominent anterior point to midline and the most prominent posterior point to midline and their ratio was compared between two ethnic groups. Each x-ray measurement was triple checked.

Results: The study groups comprised of 60 Caucasian knees and 40 Asian knees. Preoperatively the mean ratio was 0.55 in Caucasians and 0.44 in Asians, with this difference being statistically significant (p value < 0.005). Post operatively the mean ratio was 0.59 in Caucasians and 0.55 in Asians and this difference was not statistically significant (p value =0.166). These findings were also cross-checked with range of movement measurements post-operatively in the same group of patients. There was no comparable improvement in range of movements (ROM) post-operatively in the Asian group.

Conclusion: We infer that the present TKR cutting jigs are not taking into account the anatomical differences within the knee of Asians individuals. This is converting the post operative distal femurs of this group to become morphologically comparable to the Caucasian knee and this is possibly affecting the kinematics of those knees leading to no significant improvement in the post operative ROM and affecting satisfaction with surgery.

Nerve blocks are a common form of peri-operative analgesia that is administered for patients undergoing joint Replacement surgeries. The long term sequel following these peripheral nerve blocks used in total knee replacement not reported in the literature. Nerve blocks given under the guidance of nerve stimulators are in practice in most of the hospitals and are considered safe.

We report a series of two cases with residual neurological deficit following these peripheral nerve blocks in total knee replacements. In both these cases the femoral, sciatic, obturator and lateral cutaneous nerve of thigh were blocked with 0.25% of Bupivacaine with the help of a nerve stimulator.

First patient post operatively had residual numbness in the right lower leg after 4 weeks of surgery. Nerve conduction studies confirmed absent response in right Saphenous and superficial peroneal nerves. Patient has no improvement in her neurological deficit even after 16 months post operatively. Further to this she developed complex regional pain syndrome on the affected side.

Second patient post operatively developed knee extensor weakness of grade II/V and loss of sensation in femoral nerve distribution. Nerve conduction studies confirmed severe femoral nerve damage around groin. She went through a turbulent phase, knee stiffness range of movements 0–20 degrees requiring Manipulation Under Anaesthesia, later Exploration and Release of adhesions which improved her range of movements to 0–95 degrees. At 12 months post operative the neurological status improved to grade 3/5 in knee extensors.

Conclusion: Long term Complications of Peripheral nerve blocks in total knee replacements are not reported in the literature. These complications though uncommon, unfortunately for patients affect the surgical outcomes. The purpose of this case series is not only to report complications but also to share our experience of managing these complications, their outcomes and relevant literature review.