{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,30]],"date-time":"2026-01-30T04:42:06Z","timestamp":1769748126577,"version":"3.49.0"},"reference-count":12,"publisher":"BMJ","issue":"1","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2025,12,12]]},"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:p>Retropatellar (RP) chondral defects are commonly associated with trauma, sports-related injuries, or patellar dislocations. Effective management typically requires both cartilage repair and correction of underlying predisposing biomechanical factors. However, conventional imaging modalities may fail to detect subtle abnormalities.<\/jats:p>\n                  <jats:p>We describe a young female with persistent anterior knee pain in the absence of trauma or instability. Imaging studies, including radiographs and magnetic resonance imaging (MRI), confirmed an RP chondral defect, with no evidence of patella alta, malalignment or significant trochlear dysplasia. Surgical management was initiated with the focus on cartilage repair by autologous chondrocyte implantation (ACI). During first-stage arthroscopy, performed for autologous cartilage harvesting, dynamic assessment revealed a trochlear ridge impinging on the defect. This finding was considered a causative and perpetuating factor. ACI was therefore combined with mini-trochleoplasty to correct the impingement.<\/jats:p>\n                  <jats:p>This case demonstrates the diagnostic value of arthroscopy in detecting subtle biomechanical abnormalities. Surgeons should consider diagnostic arthroscopy as a dynamic tool to identify mechanical factors that may compromise cartilage repair outcomes.<\/jats:p>","DOI":"10.1136\/bcr-2025-270085","type":"journal-article","created":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T14:40:17Z","timestamp":1769697617000},"page":"e270085","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Dynamic arthroscopy in retropatellar cartilage defect: identifying trochlear ridge impingement and guiding towards mini-trochleoplasty"],"prefix":"10.1136","volume":"19","author":[{"given":"Niels","family":"Merkelbach","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery, MUMC+, Maastricht, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0579-7499","authenticated-orcid":false,"given":"Hidde D","family":"Veldman","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, MUMC+, Maastricht, The Netherlands"},{"name":"Department of Orthopaedic Surgery and Traumatology, Zuyderland Medical Centre, Sittard-Geleen, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maarten PF","family":"Janssen","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, MUMC+, Maastricht, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pieter J","family":"Emans","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, MUMC+, Maastricht, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2026,1,29]]},"reference":[{"key":"2026012906401227000_19.1.e270085.1","doi-asserted-by":"crossref","first-page":"436","DOI":"10.1007\/s00064-021-00710-1","article-title":"Prone-positioned knee arthroscopy for isolated retropatellar cartilage defects with gel-type autologous chondrocyte implantation","volume":"33","author":"Kayaalp","year":"2021","journal-title":"Oper Orthop Traumatol"},{"key":"2026012906401227000_19.1.e270085.2","doi-asserted-by":"crossref","unstructured":"Buckwalter JA . Articular cartilage injuries. Clin Orthop Relat Res 2002;21\u201337. doi:10.1097\/00003086-200209000-00004","DOI":"10.1097\/00003086-200209000-00004"},{"key":"2026012906401227000_19.1.e270085.3","doi-asserted-by":"crossref","first-page":"2444","DOI":"10.1177\/0363546519859320","article-title":"Anatomic Risk Factors for Focal Cartilage Lesions in the Patella and Trochlea: A Case-Control Study","volume":"47","author":"Ambra","year":"2019","journal-title":"Am J Sports Med"},{"key":"2026012906401227000_19.1.e270085.4","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1007\/s00167-014-3385-7","article-title":"Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects","volume":"24","author":"Mehl","year":"2016","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"key":"2026012906401227000_19.1.e270085.5","doi-asserted-by":"publisher","DOI":"10.1016\/j.arthro.2012.10.008"},{"key":"2026012906401227000_19.1.e270085.6","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-008-0635-6"},{"key":"2026012906401227000_19.1.e270085.7","doi-asserted-by":"publisher","DOI":"10.1177\/0363546513519077"},{"key":"2026012906401227000_19.1.e270085.8","first-page":"60","article-title":"Outcomes of trochleoplasty for patellar instability secondary to trochlear dysplasia: A systematic review and meta-analysis","volume":"49","author":"Tan","year":"2024","journal-title":"Knee"},{"key":"2026012906401227000_19.1.e270085.9","first-page":"3230","article-title":"Low recurrence rate and satisfactory outcomes after trochleoplasty for recurrent patellar dislocation: A systematic review and meta-analysis","volume":"29","author":"Leclerc","year":"2021","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"key":"2026012906401227000_19.1.e270085.10","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1177\/03635465251323806","article-title":"The Effect of a Supratrochlear Spur on Patellofemoral Cartilage in Patients With Trochlear Dysplasia","volume":"53","author":"Ackermann","year":"2025","journal-title":"Am J Sports Med"},{"key":"2026012906401227000_19.1.e270085.11","doi-asserted-by":"crossref","first-page":"437S","DOI":"10.1177\/1947603519897290","article-title":"Matrix-Associated Autologous Chondrocyte Implantation with Spheroid Technology Is Superior to Arthroscopic Microfracture at 36 Months Regarding Activities of Daily Living and Sporting Activities after Treatment","volume":"13","author":"Hoburg","year":"2021","journal-title":"Cartilage"},{"key":"2026012906401227000_19.1.e270085.12","doi-asserted-by":"publisher","DOI":"10.1177\/0363546515572143"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr-2025-270085","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T14:40:19Z","timestamp":1769697619000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr-2025-270085"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1]]},"references-count":12,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1,29]]},"published-print":{"date-parts":[[2026,1]]}},"alternative-id":["10.1136\/bcr-2025-270085"],"URL":"https:\/\/doi.org\/10.1136\/bcr-2025-270085","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1]]}}}