We report a case of an apparent avulsion fracture of the posteromedial margin of the medial plateau of the tibia. This was associated with a tear of the medial meniscus and rupture of the anterior cruciate ligament (ACL). This triad has been previously reported, and the plateau fracture was related to the insertion of the semimembranosus tendon. The detailed investigation of our case and some experiments on cadaver knees showed that the injury was not an avulsion fracture but was produced by varus and external rotation forces on a flexed knee. It was due to the anterior subluxation of the medial tibial plateau after rupture of the ACL

Type-I fractures of the lateral tibial plateau were simulated by osteotomy in 18 pairs of unembalmed cadaver tibiae. One fracture of each pair was fixed with two lag screws whereas the contralateral site was stabilised with three lag screws, or two lag screws plus an antiglide screw. The lateral plateau was displaced downwards using a servohydraulic materials testing machine and the resulting force and articular surface gap were recorded. Yield load was defined as the maximum load needed to create a 2.0 mm articular offset at the fracture line. The yield loads of the three-lag-screw (307 ± 240 N) and antiglide constructs (342 ± 249 N) were not significantly different from their two-screw control constructs (231 ± 227 and 289 ± 245 N, respectively). We concluded that adding an antiglide screw or a third lag screw did not provide any biomechanical advantage in stabilising these fractures

Objectives. Initial stability of tibial trays is crucial for long-term success of total knee arthroplasty (TKA) in both primary and revision settings. Rotating platform (RP) designs reduce torque transfer at the tibiofemoral interface. We asked if this reduced torque transfer in RP designs resulted in subsequently reduced micromotion at the cemented fixation interface between the prosthesis component and the adjacent bone. Methods. Composite tibias were implanted with fixed and RP primary and revision tibial trays and biomechanically tested under up to 2.5 kN of axial compression and 10° of external femoral component rotation. Relative micromotion between the implanted tibial tray and the neighbouring bone was quantified using high-precision digital image correlation techniques. Results. Rotational malalignment between femoral and tibial components generated 40% less overall tibial tray micromotion in RP designs than in standard fixed bearing tibial trays. RP trays reduced micromotion by up to 172 µm in axial compression and 84 µm in rotational malalignment models. Conclusions. Reduced torque transfer at the tibiofemoral interface in RP tibial trays reduces relative component micromotion and may aid long-term stability in cases of revision TKA or poor bone quality. Cite this article: Mr S. R. Small. Micromotion at the tibial plateau in primary and revision total knee arthroplasty: fixed versus rotating platform designs. Bone Joint Res 2016;5:122–129. DOI: 10.1302/2046-3758.54.2000481

Our aim was to compare the degree of patellar descent and alteration in angle of the inclination of the tibial plateau in lateral closing-wedge and medial opening-wedge high tibial osteotomy (HTO) in 51 consecutive patients with osteoarthritis of the medial compartment and varus malalignment. Patellar height was measured by the Insall-Salvati (IS) and the Blackburne-Peel (BP) ratios. The tibial inclination was determined by the Moore-Harvey (MH) method. Multivariate linear regression analysis was used to determine the influence of the type of HTO (closing vs opening wedge) on the post-operative patellar height or tibial inclination. The intra- and interobserver variability of these methods was determined before operation and at follow-up at one year. After an opening-wedge HTO the patellar height was significantly more decreased (mean post-operative difference: IS = 0.15; 95% confidence interval (CI) 0.06 to 0.23; BP = 0.11; 95% CI 0.05 to 0.18) compared with a closing-wedge HTO. The angle of tibial inclination differed significantly (mean post-operative difference MH = −6.40°; 95% CI −8.74 to −4.02) between the two HTO techniques, increasing after opening-wedge HTO and decreasing after closing-wedge HTO. There was no clinically-relevant difference in the intra- and interobserver variability of measurements of patellar height either before or after HTO

Fine-wire accepted as a minimally external fixation is invasive technique, which can provide better outcomes than traditional open methods in the management of complex fractures of the tibial plateau. Available fixators vary in their biomechanical stability, and we believe that a stable beam-loading system is essential for consistently good outcomes. We assessed, prospectively, the clinical, radiological and general health status of 20 of 21 consecutive patients with complex fractures of the tibial plateau who had been treated using a standard protocol, with percutaneous screw fixation and a neutralisation concept with a fine wire beam-loading fixator allowing early weight-bearing. Bony union was achieved in all patients, with 85% having good or excellent results. Full weight-bearing started during the first six weeks in 60% of patients. The general health status assessment correlated well with the knee scores and reflected a satisfactory outcome

1. Thirty-nine patients with rheumatoid arthritis who had had a MacIntosh tibial plateau hemiarthroplasty are reviewed. 2. From the clinical findings it is possible to suggest a basis for the selection of suitable patients for the procedure. 3. Eighty-five per cent of the patients obtained relief of pain with good function of the knee. 4. The complications were infection and instability of the prosthesis

Sixteen consecutive patients with tibial plateau fractures were investigated by standard radiography, biplanar tomography and computerised axial tomograms (CT scans). It was found that CT scanning proved most helpful for classifying the type of fracture, for evaluating the degree of comminution, and for measuring displacement. Moreover, because a single position was maintained throughout the investigation, the patients felt less discomfort than during other assessment procedures. For these reasons CT scanning is recommended for evaluating this type of fracture

We investigated the stability of seven Schatzker type II fractures of the lateral tibial plateau treated by subchondral screws and a buttress plate followed by immediate partial weight-bearing. In order to assess the stability of the fracture, weight-bearing inducible displacements of the fracture fragments and their migration over a one-year period were measured by differentially loaded radiostereometric analysis and standard radiostereometric analysis, respectively. The mean inducible craniocaudal fracture fragment displacements measured −0.30 mm (−0.73 to 0.02) at two weeks and 0.00 mm (−0.12 to 0.15) at 52 weeks. All inducible displacements were elastic in nature under all loads at each examination during follow-up. At one year, the mean craniocaudal migration of the fracture fragments was −0.34 mm (−1.64 to 1.51). Using radiostereometric methods, this case series has shown that in the Schatzker type II fractures investigated, internal fixation with subchondral screws and a buttress plate provided adequate stability to allow immediate post-operative partial weight-bearing, without harmful consequences

We evaluated the long-term results of 109 tibial plateau fractures, 61 treated by skeletal traction and early knee movement and 48 treated by surgery, at an average follow-up of 70 months. The functional results were much the same, though meniscectomy had been performed in almost half of the surgical patients. Time in bed and duration of hospital stay were clearly shorter after surgery (p less than 0.0001). We concluded that conservative management is a valid alternative to surgery, but should probably be reserved for cases where operation is undesirable. Future studies should compare surgery without meniscectomy and conservative treatment using cast braces to reduce the time in traction

We report the use of combined anterior and posterior approaches for the reduction and fixation of complex tibial plateau fractures involving a large split posteromedial fragment. In four patients, we used a posterior plate to fix the posteromedial fragment. All fractures united in good position with no significant complications, and all patients had a good range of knee movement. This technique should be considered for complex fractures in which there is a substantial posteromedial fragment (split) component

We treated 24 patients with high-energy fractures of the tibial plateau by the Ilizarov fixator and transfixion wires. Eleven fractures were open, and 20 patients had complex injuries. Twelve were treated by ligamentotaxis and percutaneous fixation, seven by limited open reduction and five by extensive open reduction. All were followed for at least 24 months. All the fractures united, with an average time to healing of 14.4 weeks. Thirteen patients achieved full extension and 13 more than 110° of flexion. Twenty-two knees were stable. Fifteen patients walked normally and the rest with only a slight limp. All but two knees had an articular step-off of less than 4 mm and all had normal axial alignment except two. There were no cases of postoperative skin infection, osteomyelitis or septic arthritis. Ilizarov circular fixation is an ideal method of treatment for these fractures when extensive dissection and internal fixation are contraindicated due to trauma to the soft tissue, deficiency of bone stock, and bony comminution

We carried out percutaneous, arthroscopically- and fluoroscopically-assisted osteosynthesis of fractures of the tibial plateau in 52 patients, of whom 38 were assessed using the HSS knee score and standing radiographs. We reviewed 31 AO type-B fractures and seven type-C fractures after a mean follow-up of five years (1 to 14). Fixation was achieved using percutaneous screws and/or an external frame; 33 associated intra-articular injuries, diagnosed in 21 out of the 38 patients, were treated arthroscopically. Subjectively, 94.7% of the patients reviewed were satisfied. According to the HSS knee score 78.9% of the results were excellent, 13.2% good, 7.9% fair and none was poor. Narrowing of the joint space was found in 28.9% of the injured and 5.3% of the unaffected knees and axial deviation of 5° to 10° in 15.8% of the injured and 10.5% of the unaffected knees. Of the 52 fractures, reduction was incomplete in one, and in two secondary displacement occurred, of which one required corrective osteotomy. Deep-venous thrombosis occurred in four cases. The technique has proved to be safe but demanding. It facilitates diagnosis and appropriate treatment of associated intra-articular lesions

From a search of MRI reports on knees, 20 patients were identified with evidence of early anteromedial osteoarthritis without any erosion of bone and a control group of patients had an acute rupture of the anterior cruciate ligament. The angle formed between the extension and flexion facets of the tibia, which is known as the extension facet angle, was measured on a sagittal image at the middle of the medial femoral condyle.

The mean extension facet angle in the control group was 14° (3° to 25°) and was unrelated to age (Spearman’s rank coefficient, p = 0.30, r = 0.13). The mean extension facet angle in individuals with MRI evidence of early anteromedial osteoarthritis was 19° (13° to 26°, SD 4°). This difference was significant (Mann-Whitney U test, p < 0.001).

A wide variation in the extension facet angle was found in the normal control knees and an association between an increased extension facet angle and MRI evidence of early anteromedial osteoarthritis. Although a causal link has not been demonstrated, we postulate that a steeper extension facet angle might increase the duration of loading on the extension facet during the stance phase of gait, and that this might initiate failure of the articular cartilage.

The suggestion that the knee behaves like a closed kinematic chain has been tested experimentally. The tibial joint surfaces were replaced by a deformable material and new surfaces were moulded by flexion and extension of the knee. The results support the closed kinematic chain theory; the newly moulded joint surfaces strikingly resemble the original joint surfaces. Inferences are drawn to explain why a fracture of the tibial condyle will remould with early mobilisation of the knee; why a jerk is elicited in tests for anterolateral instability; and why a flexion-compression force alone is unlikely to damage the menisci.

We performed a CT-based computer simulation study to determine how the relationship between any inbuilt posterior slope in the proximal tibial osteotomy and cutting jig rotational orientation errors affect tibial component alignment in total knee replacement. Four different posterior slopes (3°, 5°, 7° and 10°), each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were simulated. Tibial cutting block malalignment of 20° of external rotation can produce varus malalignment of 2.4° and 3.5° with a 7° and a 10° sloped cutting jig, respectively. Care must be taken in orientating the cutting jig in the sagittal plane when making a posterior sloped proximal tibial osteotomy in total knee replacement.

Cite this article: Bone Joint J 2013;95-B:1201–3.