BACKGROUND:Compared with total knee arthroplasty,unicondylar knee arthroplasty has such advantages as quick recovery,low cost and good proprioception,but its high revision rate after operation is also a problem that cannot be ignored.At present,the reasons for the high revision rate after unicondylar knee arthroplasty are not completely clear.Therefore,preoperative strict control of surgical indication may be crucial to improve postoperative outcome and reduce revision rate after unicondylar knee arthroplasty.As an index commonly used in the measurement of imaging,the evaluation of joint space width may have important clinical reference value in the selection of indications for unicondylar knee arthroplasty. OBJECTIVE:To review the measurement of joint space width and its effect on the curative effect and outcome of medial unicondylar knee arthroplasty. METHODS:WanFang and PubMed were used to search the relevant literature published from January 1,1950 to June 1,2023 on the evaluation factors of curative effect of unicondylar knee arthroplasty and the influence of joint space width on the curative effect of unicondylar knee arthroplasty.By summarizing and analyzing the literature,the measurement methods of joint space width,the influence of preoperative medial compartment joint space width on the curative effect of medial compartment joint space width,and the influence of postoperative lateral compartment joint space width on the outcome were reviewed. RESULTS AND CONCLUSION:(1)Although many methods have been used to study and measure knee joint space width,X-ray measurement of joint space width under weight-bearing position is still a common method in daily orthopedic practice to assess the progression of osteoarthritis,and it can moderately reflect the thickness of cartilage.(2)Preoperative medial compartment joint space width of knee joint can affect the efficacy of medial movable platform after unicondylar knee arthroplasty.Patients with knee osteoarthritis whose medial joint space width/lateral joint space width ratio is<40%or medial joint space width≤2 mm may be more suitable for medial movable platform unicondylar knee arthroplasty.(3)Changes in lateral compartment joint space width after medial unicondylar knee arthroplasty also have a certain impact on outcome.Improving the joint matching degree of lateral compartment after surgery can delay the progression of lateral compartment joint degeneration and reduce the prosthesis revision rate.However,relevant clinical studies are still lacking.In conclusion,the imaging measurement of joint space width has important clinical reference value for evaluating the postoperative efficacy and prognosis of medial unicondylar knee arthroplasty.