Osteotomy and Joint Preservation

Osteotomy planning starts with pain and the affected compartment, then distinguishes femoral, tibial, and intra-articular sources of deformity. Look beyond the overall limb angle to MPTA, LDFA, and JLCA.

The correction target considers load distribution, remaining cartilage, ligament condition, and activity goals. Excessive correction in one bone can produce marked joint line obliquity. Also review positioning on weight-bearing images and measurement error.

HTO planning requires both calculation of weight-bearing-line transfer and analysis of where the deformity originates. Separate femoral, tibial, and intra-articular JLCA contributions, and document the affected cartilage compartment, ligament laxity, and activity goals. Differences between weight-bearing and stress imaging can inform estimates of the overall alignment achievable from the planned bony correction, but measurement conditions and the validation scope of the prediction method must be checked.

Do not apply the historical Fujisawa point uniformly to every varus knee. The ESSKA consensus also emphasizes individualized targets based on OA severity and indication and assessment of joint-line orientation. If a large tibial correction is expected to create nonphysiological joint-line obliquity, assess femoral deformity and double-level correction together. Record the remaining cartilage and joint environment as the basis for the plan, rather than relying on angle values alone.

Correction in opening-wedge HTO is not confined to the coronal plane. The relationship between anterior and posterior gaps and the hinge position affects posterior tibial slope. How the tibial tubercle is included affects patellar height.

The retro-tubercle biplanar technique is one way to address patellar height. Assess the benefit of maintaining imaging measures alongside the risks of tibial tubercle fracture and healing problems. Differences in radiographic measures observed in comparative studies do not by themselves establish clinical superiority.

The anterior and posterior opening gaps, hinge, and osteotomy plane in an opening-wedge procedure are related to changes in tibial slope. Posterior cortical and soft-tissue conditions and the actual movement at the osteotomy also contribute, so a simple gap ratio cannot guarantee slope control in every patient. If cruciate-ligament dysfunction or concomitant reconstruction is present, planning should also assess how slope changes affect instability and graft loading.

For patellar height, distinguish the reference used by each index. Changes in tibial tubercle position and the joint line may affect the indices differently, so maintain consistent imaging and measurement methods. When comparing tubercle-preserving biplanar or retro-tubercle techniques, assess tubercle fracture, union, fixation, and clinical outcomes alongside preservation of height. Successful coronal correction does not replace assessment in the other planes.

The hinge provides stability during correction and affects fracture propagation. Review osteotomy location, hinge integrity, opening size, fixation, and bone quality together. Similar gap sizes do not necessarily imply the same conditions for healing and loading.

Decisions about filling a bone defect and increasing weight bearing depend on fixation stability, hinge injury, and the patient’s condition. Follow-up distinguishes loss of correction, bone union, and implant problems. A weight-bearing schedule reported in a study should be interpreted in light of that study’s fixation method, patient population, and healing conditions.

The hinge is not merely a pivot point; it influences correction stability and fracture risk. Assess the location of the lateral hinge, remaining cortex, correction magnitude, bone quality, and plate construct together. If a hinge fracture occurs, distinguish its location, extension into the articular surface, and instability; the same weight-bearing schedule cannot be assigned on the basis of a name or classification alone.

During follow-up, assess union, maintenance of correction, and pain around the implant separately. Differences in imaging rotation, flexion, and weight-bearing can mimic changes in angle, so confirm consistent conditions. Bone graft or substitute use should reflect fixation, bone quality, and healing conditions rather than gap size alone. Teach progression of loading and exercise with the procedure, hinge condition, serial imaging, and symptoms recorded as its basis.

Double-level osteotomy distributes correction between the femur and tibia to control both overall limb alignment and joint-line orientation. Correcting a large varus deformity entirely through the tibia may achieve the target HKA while creating excessive MPTA and joint-line obliquity. A large correction angle alone does not establish the indication. Identify the symptomatic compartment and the feasibility of joint preservation, then analyze how deformity is distributed between the two bones.

Begin with mLDFA, MPTA, and JLCA measured on standardized weight-bearing long-leg radiographs. Separate bony deformity from contributions of joint-space loss and ligament laxity. Draw and compare the predicted HKA, MPTA, and joint-line orientation after isolated HTO and double-level correction. Assumptions about postoperative reduction of intra-articular deformity affect the required bony correction. Do not interpret measurement differences caused by imaging rotation or flexion as an additional deformity.

Allocate femoral and tibial correction to satisfy both the overall load-axis target and the joint angles of each bone. Evaluate osteotomy gaps, hinge locations, and fixation feasibility alongside joint-line obliquity in the plan. A particular MPTA limit may be a study-selection criterion or planning aid rather than a universal surgical threshold. Consider native morphology, cartilage condition, ligament function, and sagittal and rotational deformity when predicting the postoperative joint environment.

Comparative clinical studies suggest that double-level osteotomy can preserve a more physiological joint line in substantial combined varus deformity, but superiority across all functional scores and return-to-activity outcomes is inconsistent. Consider union and fixation at both osteotomies, neurovascular risk, and rehabilitation demands. Follow-up should separately assess the overall axis, individual joint angles, union, maintenance of correction, and symptoms. A more horizontal joint line on imaging and functional benefit to the patient are distinct outcomes.

Lateral closing-wedge HTO corrects varus by removing a lateral bone wedge and closing the osteotomy. Medial opening-wedge HTO creates correction by opening a medial gap. Both aim to reduce medial-compartment loading, but they differ in their effects on bone stock, limb length, and surrounding soft tissues. Confirm that symptoms correspond to the medial compartment and that lateral cartilage and ligament function can accommodate correction, then select the approach suited to the deformity and goals.

Closing-wedge osteotomy provides apposition of bone surfaces but requires attention to the proximal tibiofibular joint, fibula, and protection of the peroneal nerve; bone stock and length can decrease. Opening-wedge osteotomy permits gap adjustment without directly cutting the fibula but requires consideration of fixation, healing of the gap, and the lateral hinge. Neither a need for grafting in every large gap nor universally faster union after closing-wedge osteotomy should be assumed. Compare bone quality, correction magnitude, and fixation constructs together.

Even with the same coronal target, posterior tibial slope, patellar height, and limb length may change differently. A tendency toward reduced slope after closing-wedge surgery has been reported, but osteotomy geometry, hinge, and fixation affect the result. Slope and patellar-height changes after opening-wedge surgery are also technique-dependent. Include cruciate-ligament status, preexisting patella baja, extensor symptoms, and future arthroplasty planning; measure sagittal alignment and tubercle relationships consistently before and after surgery.

Randomized comparisons found similar mid-term pain, function, and alignment maintenance, with differences in complications and conversion to arthroplasty. Do not generalize results from particular fixation devices and surgical eras to every modern technique. Follow-up should assess union, maintained alignment, neurological symptoms, hardware irritation, and actual walking function. Base selection on deformity location, length and slope goals, and treatment circumstances, rather than survival from one study alone.