Patients and preoperative evaluation
Patients with HTPF treated with rim plates between April 2015 and December 2019 were retrospectively analyzed. All the patients were minimally followed up for one year. HTPF was defined by medial and/or lateral decompression of the anterior plateau with decreased posterior slope angle (PSA). Patients with pathological and chronic fractures were excluded. Patients with multiple injuries or with accompanying fractures were also excluded. This study was approved by the ethical committee of Beijing Jishuitan Hospital.
All the patients were temporarily immobilized with casts, braces, or external fixator at the emergency admission. Preoperative radiographs and CT scans were taken for all patients to evaluate the morphological characteristics of the fracture. The definite surgical treatment of open reduction and internal fixation was carried out when the soft tissue condition permitted, i.e., when blister faded and swelling improved, which was evaluated by the surgeon.
For patients whose fractures only involved the medial or lateral plateau, a single anteromedial or anterolateral approach was used. Also, for patients with bicondylar fracture, anteromedial/posteromedial and anterolateral approaches were most commonly used. A posterior tension fracture was usually found in patients with bicondylar HTPF, for whom the posteromedial incision was firstly made to expose and reduce the posterior fracture, after which it was fixed with a 1/3 tubular plate or anatomical plate with a short proximal screw to allow minimal transition when elevating the anterior decompression, thus providing a hinge point. Next, reduction of the anterior depressed articular surface to restore the sagittal and coronal alignments was performed mainly following the approach described by Firoozabadi et al . Simply, an osteotome or spreader was inserted to the impaction area of the anterior metaphysis and was elevated until the PSA was restored. Reductions by multiple Kirschner wires or plates described were also found to be effective methods. For HTPF patients whose fractures only involved medial or lateral plateau, the reduction was performed in the same way. Once satisficed reduction was achieved and verified by intraoperative fluoroscopy, provisional stabilization was performed using Kirschner wires. Structural artificial bone augments (MIIGTM X3 or PRO-DENSETM Injectable, Wright Medical Technology, Inc., Memphis, USA) were used if the anterior defect was >1 cm.
For the fixation of the anterior reduced plateau, the anteromedial and/or anterolateral locking plates (Synthes GMBH, Oberdorf, Switzerland) were first used. In addition, to further buttress the “bare area” behind and close to the patella tendon, a 2.7mm plate (Synthes GMBH, Oberdorf, Switzerland) was pre-contoured to adapt to the curve of the anterior plateau, after which it was inserted behind the patella tendon above the locking plate. Finally, screws of convenient length were inserted at one/each side of the patella tendon parallel to the articular surface. At least 1 long screw was placed to the posterior fragment or the uncomminuted medial/lateral fragment to prevent secondary loss of reduction (Figure 2, 3).
Postoperative radiographs and CT scans were obtained. Also, passive and active rehabilitation, including a full range of motion (ROM), was arranged early after surgery. Usually, non-weight bearing lasted for 4 to 6 weeks and was followed by partial-weight bearing. Full-weight bearing was only allowed when bone healing was verified by radiographs. The medial tibial plateau angle (mTPA) and PSA were measured on standard radiographs at immediate post-operation and the last follow-up by two authors (Zhijian Sun and Changrun Li) . Major complications were recorded, and clinical outcomes were assessed by the hospital for special surgery (HSS) knee score at the last follow up.