Objective:To investigate the efficacy of internal fixation of Pipkin types I and II femoral head fractures through the modified Smith-Petersen (S-P) approach.Methods:A retrospective case control study was conducted to analyze the clinical data of 33 patients with Pipkin types I and II femoral head fractures admitted to Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology from June 2015 to September 2019. There were 22 males and 11 females, aged 20-40 years (mean, 29.5 years). There were 15 patients with Pipkin type I fractures and 18 with Pipkin type II fractures. A total of 22 patients were treated using the modified S-P approach via the sartorius and tensor fascia lata space (modified S-P group) and 11 patients were treated using the modified K-L approach via the posterior superior iliac spine and gluteus maximus (modified K-L group). The operation duration, intraoperative blood loss, postoperative drainage volume, length of hospital stay, numeric rating scales (NRS) for pain assessment at postoperative 15 days, bone healing time, Harris hip joint score at postoperative one month, and complication rate were compared between the two groups.Results:All patients were followed up for 1-24 months (mean, 6.5 months). The operation duration, blood loss, drainage rate and length of hospital stay in modified S-P group were better than those in modified K-L group [(71.7±7.3)minutes vs. (112.1±6.7)minutes, (55.9±6.2)ml vs. (99.4±8.7)ml, (91.2±5.9)ml vs. (121.3±7.0)ml, (6.0±1.5)days vs. (10.5±1.6)days] ( P<0.01). There were no significant differences between two groups in terms of NRS, bone healing time and Harris score ( P>0.05). The incidence of complications was similar between the two groups, including femoral head ischemia necrosis, traumatic arthritis, and heterogenous ossification ( P>0.05). Conclusion:For Pipkin types I and II femoral head fractures, the modified modified S-P approach is superior to modified K-L approach in aspects of operative time, intraoperative blood loss, postoperative drainage and length of hospital stay.