Trans-tibial amputation (Below-knee amputation) that involves removing the foot, ankle joint and distal tibia and fibula with related soft tissue structures . Amputations occurs due to variety of reasons including trauma, diseases, tumors, infections and congenital malformations .Traumatic amputations tend to occur in younger and active age and in Pakistani amputee population the majority 65-70% the cause of amputation is traumatic and 50-60% are Trans-tibial amputations. Several complications related to the amputation-prosthesis interface needs attention while managing amputees including joint full range of motion especially in the joint immediately proximal to the amputation site. The trans-tibial amputees are prone to develop flexion deformity of the knee . Normal active range of motion of the knee is 0° extension and 140° flexion. In many people after Tran's tibial amputation with a flexion deformity, active range of motion of the ipsilateral knee is reduced . The main cause of occurrence of flexion deformity of the knee is the muscle shortening and tightness especially the hamstrings muscles due to the long periods in a bending position or inactivity due to the illness or lack of exercise .

Muscle Energy Techniques are used for lengthening of the muscles and improve range of motion (ROM) in joints . Active Isolated Stretching (AIS) is a uniquely effective exercise system with the advantages of specificity, active initiation, Incremental assists, Gentle motion, Brief duration, Multiple repetitions and Deep breathing. To stretch the hamstring muscles by lifting the leg straight up, stay on the mid-sagittal plane (keep the legs parallel). If the leg rotates out to the side, you lose much of the hamstring stretch and start affecting other muscles instead . While In Post Facilitation Stretch technique the hypertonic and shortened muscle is placed between a fully stretched and a fully relaxed state. Contracture of hamstrings using a maximum degree of effort for 5-10 seconds while the therapist resists the force. After this relaxation is done and effort is released and the therapist applies a rapid stretch to a new barrier and is held for 15 seconds. The relaxation is for 20 seconds and the procedure is repeated between three to five times and five times more .

Study concluded that the AIS helps to restore the deteriorated flexibility of the muscles . In 2013 study concluded compare the Muscle Energy Techniques with static stretches' for increasing hamstring flexibility in post burn patients. Their results shows that Both treatment groups had highly significant gains in knee extension ROM after 5 and 8 days post stretching exercises. But MET had highly significant gains in knee extension ROM than static stretching after 8 days of treatments .

In 2014 studied the three groups of 60 male students of Semnan University of Medical Sciences having shortened hamstring muscles. The 1st group underwent the hold relax technique, 2nd group underwent static stretches' and the 3rd group with no interventions for 4 weeks and three times a week. Results were recorded with goniometer before and after the sessions. Their results showed that both methods have a significant effect on increasing the motion range of knee. But no significant difference was observed between the static stretch and hold-relax techniques .

In 2019 study reviewed 4 studies related to active isolated stretches' for knee extension who evaluated 53 subjects who performed knee extension stretches 4 times a week for 4 weeks. The increase in ROM was statistically significant after the 1st week of AIS and in static stretches after 2 to 4 weeks. The AIS increase in ROM was significantly greater than for the static stretch exercise. Another study studied 30 subjects and their results showed that both modes of stretching significantly increased ROM, but AIS increased ROM significantly more than the static stretch exercise. Another study evaluated 30 subjects and reported that only the AIS significantly increased ROM. study reported on 30 subjects concluded that AIS increased ROM more than 11% versus the 8% by static stretch but the difference was not statistically significant .