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Postoperative mechanical axis linked with patellofemoral degenerative progression after high tibial osteotomy

Among patients who underwent opening-wedge high tibial osteotomy, postoperative mechanical axis, which may be the result of overcorrection, was linked to patellofemoral degenerative progression.

Researchers identified 86 patients (total of 98 knees) who underwent hardware removal with second-look arthroscopy 21.4 months after opening-wedge high tibial osteotomy performed with first-look arthroscopy. The mean follow-up was 49.8 months. Investigators evaluated predictive factors for patellofemoral degeneration which included demographics, preoperative and postoperative mechanical axis of the lower limb, tibial slope and modified Blackburne-Peel ratio. Based on their patellofemoral degenerative progression from first to second arthroscopy, patients were categorized into either a progression or non-progression group. Clinical outcomes were compared between the groups.

Results showed the most significant factor for progressive change in the patellofemoral joint was the postoperative mechanical axis. There were 28 knees with patellofemoral degenerative progression. The mean postoperative Kujala score was lower in the progression group compared with the non-progression group (60.5 vs. 72.3). The KOOS scale scores were also lower in the progression group vs. the non-progression group, with the exception of the symptom subscale. The mean postoperative mechanical axis corrected in progression group compared with the non-progression group was -5.1° vs. -2.4°. – by Monica Jaramillo

Disclosure: The study was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea, grant number HI15C242.

Among patients who underwent opening-wedge high tibial osteotomy, postoperative mechanical axis, which may be the result of overcorrection, was linked to patellofemoral degenerative progression.

Researchers identified 86 patients (total of 98 knees) who underwent hardware removal with second-look arthroscopy 21.4 months after opening-wedge high tibial osteotomy performed with first-look arthroscopy. The mean follow-up was 49.8 months. Investigators evaluated predictive factors for patellofemoral degeneration which included demographics, preoperative and postoperative mechanical axis of the lower limb, tibial slope and modified Blackburne-Peel ratio. Based on their patellofemoral degenerative progression from first to second arthroscopy, patients were categorized into either a progression or non-progression group. Clinical outcomes were compared between the groups.

Results showed the most significant factor for progressive change in the patellofemoral joint was the postoperative mechanical axis. There were 28 knees with patellofemoral degenerative progression. The mean postoperative Kujala score was lower in the progression group compared with the non-progression group (60.5 vs. 72.3). The KOOS scale scores were also lower in the progression group vs. the non-progression group, with the exception of the symptom subscale. The mean postoperative mechanical axis corrected in progression group compared with the non-progression group was -5.1° vs. -2.4°. – by Monica Jaramillo

Disclosure: The study was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea, grant number HI15C242.

    Perspective
    Vicente Sanchis-Alfonso

    Vicente Sanchis-Alfonso

    Several papers published recently are warning us about the patellofemoral chondropathy progression after an open-wedge high tibial osteotomy (OWHTO), although the clinical consequences of those degenerative changes are still unclear. In fact, several studies have shown that the patellofemoral chondropathy progression after OWHTO did not affect clinical outcomes. Following this line of research, the objective of Lee and colleagues is to identify risk factors for patellofemoral degenerative progression after OWHTO and to investigate the effect of patellofemoral degeneration on the outcomes. These authors have evaluated the patellofemoral degenerative progression by means of a second-look arthroscopy and have observed that the progression of degenerative changes is correlated with an overcorrection of the mechanical axis in valgus. Furthermore, they have reported that this progression relates to poorer patient-reported outcomes.

    I agree with the findings observed by Lee and colleagues. The results they present make perfect sense, since any variation of the normal skeletal alignment, in any of the three planes — coronal, sagittal and transverse — may increase the forces acting on the patellofemoral joint causing either ligament failure or cartilage failure and subsequently patellofemoral osteoarthritis. Anterior knee pain may result from these abnormal forces or their consequences. It is well known that skeletal malalignment in the frontal plane influences the progression of patellofemoral osteoarthritis. Therefore, when we perform an OWHTO we must avoid overcorrection. The first goal of a coronal plane osteotomy is to restore a neutral mechanical axis. If there is some articular deterioration medially, the new mechanical axis must fall near the lateral tibial spine, not beyond. If there is no medial articular damage, the new mechanical axis should be between the two tibial spines. The second goal would be to keep the joint line horizontal.

     

    • Vicente Sanchis-Alfonso, MD, PhD
    • Department of orthopedic surgery
      Hospital Arnau de Vilanova
      Valencia, Spain

    Disclosures: Sanchis-Alfonso reports no relevant financial disclosures.

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