The Complications Committee of the Arthroscopy Association of North America formulated a registry to investigate complications associated with arthroscopy . The overall complication rate in this study was 1.68%. Of the complications recorded, haemarthrosis occurred with a frequency of 60.1%. The actual significance of haemarthrosis has been debated . Not only is there a toxic effect on the articular cartilage by the haemarthrosis but the susceptibility to infection is increased in its presence. In addition, it has been documented that in certain arthroscopic procedures the occurrence of haemarthrosis results in the scar formation, decreased range of motion, subsequent synovitis and delayed rehabilitation .
In our study the grade of the haemarthrosis and post – operative pain was significantly higher in the double bundle ACL group than the SB ACL group. This difference can be attributed to following factors associated with DB ACL reconstruction group i.e. increased surgical time (n = 74.7 min.), the numbers of tunnels drilled are doubled, in 46% of cases notchplasty was done due to graft impingement of the Antero Medial bundle (AM) on extension, this is especially true as more area is taken up in the intercondylar notch due to 2 grafts in the DB ACL reconstruction.
The significant difference in the range of motion between DB and SB ACL groups noted in terms of loss of terminal extension and difference in muscle bulk at the end of 4th week between the two groups can be attributed to the increased haemarthrosis and pain post – operatively leading to delayed rehabilitation of quadriceps.
Most of the studies which had compared difference in ROM and / or thigh circumference between DB ACL and SB ACL didn’t report significant difference on a long term follow-up, [9, 10] but no study has compared the results in the initial 6 months of rehabilitation. McCormack et al  measured ROM and or thigh circumference in cases of SB ACL reconstruction only with and without drain and didn’t find any statistically significant difference at 1,4, 8 weeks.
The numbers of menisectomies done in both these groups were statistically similar and thus did not influence the result of our study.
Muscular strength was evaluated using the isokinetic machine at 12 and 24 weeks and there was a statistically significant difference in muscle strength deficit in the SB ACL group as compared to the DB ACL group. The SB ACL group had statistically significant better muscle strength at 3 months in the quadriceps muscle groups. This again can be attributed to pain and haemarthrosis post operatively in the DB ACL group delaying rehabilitation.
The results for quadriceps weakness can be explained due to relative inactivity and ineffective strengthening exercises following surgery which leads to type II muscle fibre atrophy [12–16]. Also the patients with ACL reconstruction demonstrate arthrogenic quadriceps inhibition in order to minimise anterior tibial translation and ACL graft strain . During ACL reconstruction the gamma loop function could be attenuated in the quadriceps because the mechanoreceptors in the ACL are not surgically reconstructed [5, 18]. In contrast to the quadriceps, the hamstrings are less susceptible to strength deficits following an ACL injury. These deficits are thought to be due to bi-arthrodial nature of three of the four hamstring components such that even when knee mobility is impaired following in ACL injury, hip extension continues to act as stimulus for the hamstrings [19–22]. Also the current rehabilitation protocols emphasis early and aggressive hamstring training following an ACL reconstruction [23–26] on the basis that hamstring contraction can produce posterior tibial translation to reduce the strain on the maturing ACL substitute . While using semitendinosus and gracilis tendon autograft, recovery of hamstring strength is of some concern given that the semitendinosus tendon is sacrificed during the procedure  but most of the investigators have generally found non-significant hamstring deficits between the operated and non-operated site in the post-operative period [27–29].