A Supratuberosity Anterior Closing-Wedge Proximal Tibial Osteotomy Increases Patellar Height: A Simulated Time Zero Uniplanar Radiographic Study

Editorial Commentary: Different Levels for Posterior Tibial Slope Reducing Anterior Closing Wedge Osteotomy to Reduce Anterior Cruciate Ligament Reconstruction Failure Present Different Risks

It has become increasingly recognized that a steep posterior tibial slope is a modifiable risk factor for the failure of an anterior cruciate ligament reconstruction. An anterior closing wedge osteotomy (ACWO) may be performed to flatten the slope, and this osteotomy may be performed above, through, or below the tibial tuberosity. A supra-tuberosity technique may increase the patellar height. However, this increase may be modest, may not affect the clinical outcomes, and is only one risk that I would consider when deciding whether to perform an ACWO above, through, or below the tibial tuberosity. The short proximal fragment of supra-tuberosity ACWO mandates a short anterior cruciate ligament reconstruction tibial tunnel and may compromise fixation of the osteotomy. A trans-tuberosity ACWO usually requires a tibial tuberosity osteotomy, which requires slower postoperative mobilization and risks nonunion or fracture of the tibial tubercle. And, an infra-tuberosity ACWO has lesser healing potential than a more proximal osteotomy.

The Influence of Tibial Tubercle-Sparing Slope-Reducing Osteotomy on Patellar Height in Patients Undergoing Revision ACL Reconstruction

BACKGROUND

A posterior tibial slope (PTS) >12° is an independent risk factor for anterior cruciate ligament (ACL) graft rupture, and a high tibial osteotomy (HTO) for slope correction can help avoid it. Management of patellar height is of major concern when performing HTO.

PURPOSE

To evaluate the effect of tibial tubercle-sparing anterior closing-wedge osteotomy on patellar height in revision ACL reconstruction (ACLR).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent arthroscopic revision ACLR combined with retro-tibial tubercle anterior closing-wedge HTO (ACW-HTO) between January 1, 2016, and March 31, 2021, were assessed for eligibility. Patellar height was measured on full weightbearing lateral radiographs according to the Insall-Salvati index (ISI) and Caton-Deschamps index (CDI) or frontal radiographs using the femoral patellar height index. The PTS was evaluated using the proximal anatomic axis of the tibia on standard short lateral radiographs. The delta (postoperative - preoperative) and the ratio (preoperative/postoperative) of the 3 patellar height indices and PTS were calculated. Preoperative and postoperative patellar heights were compared using independent t tests for each index. Also investigated was whether patients changed patellar height category (baja, normal, or alta) after slope osteotomy.

RESULTS

Among 475 revision ACLRs, 47 tibial tubercle-sparing ACW-HTOs were retained for analysis. No significant difference in patellar height was found between pre- and postoperative radiographs regardless of the index (preoperative - postoperative) (ISI: 1.0 ± 0.2 - 0.9 ± 0.2, P = .1729; CDI: 1.0 ± 0.2 - 1.0 ± 0.2, P = .4034; femoral patellar height index: 1.5 ± 0.2 - 1.5 ± 0.2; P = .5130). Fifteen patients (31.9%) exhibited a postoperative change in their patellar height category when measured by the ISI (6 moved up a category, 9 moved down one), and 18 patients (38.3%) changed category according to the CDI (10 moved up a category, 8 moved down one). No significant difference was found between pre- and postoperative patellar height among these patients (ISI: P = .2418; CDI: P = .3005).

CONCLUSION

Changes in patellar height ratio are common after tibial tubercle-sparing ACW-HTO in patients undergoing revision ACLR. The clinical effect of these changes is unknown, and further study is needed to investigate whether they may result in patellofemoral symptoms.