ObjectiveTo investigate the effectiveness of arthroscopic treatment for combined injury of the posterior horn of the medial meniscus (PHMM) and the anterior horn of the lateral meniscus (AHLM). MethodsBetween September 2009 and December 2012, 36 patients (36 knees) with combined injury of PHMM and AHLM underwent arthroscope surgery. There were 16 males and 20 females with an average age of 47 years (range, 30-64 years), and a median disease duration of 30 months (range, 3 months-9 years). The left knee was involved in 14 cases and the right knee in 22 cases. Two patients had a history of sprain, and other patients had no obvious incentive. The patients had limited activity of the knee in varying degrees; posterior medial tenderness in the medial knee joint space and positive Mcmurray tests were found in all cases, and anterior tenderness in the lateral knee joint space in 26 cases. Effusion of the knee joint occurred in 5 cases. The X-ray and MRI before operation indicated injury of PHMM combined with injury of AHLM in 30 cases and simple injury of PHMM in 6 cases; meniscal cyst was found in 2 cases, and popliteal cyst in 1 case. Partial meniscectomy was used for PHMM, the external-inner suture or partial meniscectomy was used for AHLM. ResultsAll incisions healed primarily with no complication. All cases were followed up 22.5 months on average (range, 10-40 months). At last follow-up, the patients had no pain, weakness, and instability, and tenderness in medial and lateral joint space disappeared. Except 4 patients who had weakly positive Mcmurray test, the results of Mcmurray test were negative in the others. Based on the improved Lysholm classification standard, the results were excellent in 25 cases, good in 8 cases, and fair in 3 cases; the excellent and good rate was 91.7%. ConclusionArthroscopic primary repair of combined injury of PHMM and AHLM can effectively recover the knee function with a better effectiveness.