The aim of this study is to investigate the point or nonsense of treating cartilage lesions at the level of the first metatarsophalane joint. To date, no clear guidelines have been found in the literature with regard to the treatment of cartilage lesions at the MTP I joint during corrective surgery for hallux valgus, nor has it been investigated whether this can have an effect on the clinical outcome.

A randomized, single surgeon study in which two groups will be compared with each other:

Group 1: 50 patients in whom no treatment of the cartilage lesions is performed: these patients have no cartilage lesion or a grade I cartilage lesion at the MTP I joint that has been found to be operative. The grade of the cartilage lesions will be determined on the basis of the ICRS scale and an MS Hololens.

Group 2: 50 patients with a cartilage lesion> grade 1 found during surgery. Whether or not to treat the cartilage injury will be randomly determined. 50 envelopes will be made with 25 treat, 25 not to treat. Just before surgery, Dr. T. Lootens an envelope will be drawn which will determine the further policy of the operation:

Group 2A: 25 patients who are not treated for the cartilage injury. Group 2B: 25 patients who are treated for the cartilage injury by means of debridement of the lesion and microfracture.

The patients who will undergo surgery for hallux valgus will be seen pre-operatively at the outpatient clinic by the investigators. During this consultation, an explanation will be given about the research and the participant will have to sign an informed consent before participating in the study. Here, the participant will also receive an envelope with questionnaires (AOFAS score / SF 36 score / VAS pain and satisfaction), which they will fill out on the day of surgery.

Follow up The participants will be seen again at the orthopedics outpatient clinic for clinical follow-up and filling out questionnaires at 10 days, 5 weeks, 4 months and 1 year postoperatively. This follow up will be done by the co-investigator, who is blinded during the study.

Scientific foundation Corrective hallux valgus surgery currently exists in two ways: open and closed (percutaneous) technique. To date, there is no consensus on the treatment of visible cartilage lesions at the MTP I joint during the open technique. It is not known whether or not treating these injuries has an impact on the patient's clinical outcome. The Principle investigator already treats the serious cartilage lesions (> GR1 lesions) by means of debridement of the lesion, followed by microfracture. As there is no literature available on this topic yet, this research could certainly add value for the therapeutic approach of cartilage lesions at MTP I in the future.

Moreover, if microfracture gives a significantly better clinical outcome, this means that the closed (percutaneous) technique is contraindicated as a corrective technique in patients with hallux valgus. If this is not the case, no cartilage lesions at the level of the MTP I joint need to be taken into account during open technique.

Inclusion Criteria:

• hallux valgus

Exclusion Criteria:

• younger than 30 years, older than 60 years
• extra pathologies other than hallux valgus