Abstract
Background:
Tibial tubercle osteotomy and distal realignment allows for adjustment to the patellofemoral articulation in order to improve patellar tracking and redistribute patellar contract pressures.
Indications:
A healthy, active 39-year-old woman status post right knee tibial tubercle osteotomy presented with >2 years of patellar instability symptoms in the left knee. Imaging revealed a tibial tubercle to trochlear groove (TT-TG) distance of 21 mm and patellar tendon lateral trochlear ridge (PT-LTR) distance of 14 mm.
Technique Description:
After knee arthroscopy is performed, an open incision is made along the inferomedial patellar tendon. Two pilot holes are created before a sagittal saw is used to make the tibial tubercle osteotomy, before completing it with an osteotome. Anteromedialization and/or distalization of the osteotomy is performed relative to templated values in order to improve patellar articulation. After correction, 3 bicortical screws are placed to achieve stable fixation.
Results:
There were no immediate complications following surgery. Surgical management led to improvement of the patient’s patellofemoral pain, which allowed return to prior baseline level of function.
Discussion/Conclusion:
The preferred technique for an anteromedialzing tibial tubercle osteotomy is presented. An anteromedializing tibial tubercle osteotomy is an effective surgical option for patients with evidence of patellar maltracking or central or lateral patellar chondromalacia whom have failed conservative management. This case demonstrates the efficacy of an anteromedializing tibial tubercle osteotomy to provide pain relief by improving patellar tracking and offloading patellar contact pressures on areas of prominent chondral wear.
This is a visual representation of the abstract.
Keywords
Video Transcript
In this video, we will discuss the indications, surgical technique, and outcomes for an anteromedializing tibial tubercle osteotomy.
Here are our disclosures.
The following topics will be covered in this video.
We will utilize a case presentation to demonstrate the indications for a tibial tubercle osteotomy. Our patient is a 39-year-old woman who previously had a right knee anteromedializing tibial tubercle osteotomy 6 years prior with great results. She developed similar patellar instability symptoms in her left knee that have been prominent for over 2 years. These included subjective subluxation events and progressively worsening patellofemoral pain and effusions with activities, such as hiking. These symptoms persisted despite greater than 3 months of physical therapy and pain management. On examination, her left knee had a mild effusion, patella crepitus, and patella tenderness.
Radiographs were acquired, which were largely normal. She was measured to have a Caton-Deschamps index (CDI) of 1.16. Left knee magnetic resonance imaging (MRI) subsequently demonstrated a shallow trochlear groove, tibial tubercle to trochlear groove (TT-TG) distance of 21 mm, and a patellar tendon-lateral trochlear ridge (PT-LTR) distance of 14 mm. The PT-LTR distance reflects the vectors that pull the patella into lateral maltracking and > 6.5 mm is abnormal. 6 MRI also revealed areas of partial-thickness patellar cartilage loss, and for this reason we routinely scope patients first during the case to smooth loose chondral flaps and remove any loose bodies. Of note, an inferomedial patella chondral lesion due to relocation after patella dislocation is not a contraindication to anteromedialization when this is done as part of a patella stabilization procedure along with medial patellofemoral ligament reconstruction.
Based on the patient’s clinical symptoms, examination, and imaging she was determined to be a candidate for a tibial tubercle osteotomy. We aimed to medialize the patella by 11 mm and anteriorize the patella by utilizing a 55° angled cut. Distalization was not determined to be necessary, as the patient had a normal CDI index. Other relevant contraindications to our proposed surgical plan would have included normal TT-TG distance and medial patellofemoral chondrosis without concomitant cartilage restoration.
This procedure was performed on an outpatient basis under regional anesthesia. Requisite materials for the tibial tubercle osteotomy procedure are listed here. The patient is positioned supine on a regular operating room table. We use a nonsterile thigh tourniquet in order to reduce bleeding intraoperatively.
A 6-cm incision is made over the medial border of the tibial tubercle, extending distally from the inferior portion of the patellar tendon. Full thickness flaps are created medial and lateral to the patellar tendon insertion, which is defined by dissection along its undersurface to expose the anterior proximal tibia. Along the lateral side of the patellar tendon, the proximal 1 to 2 cm of anterior compartment fascia distal to Gerdy tubercle is incised to allow an osteotome to be slid between the fascia and muscle, avoiding the need to strip the anterior compartment muscle from the tibia.
Two unicortical pilot drill holes are created with a 3.2-mm drill in the center of the anticipated 5-cm osteotomy site. Room for a third screw is left between the pilot drill holes. Rotation of the leg is confirmed by examining the position of the foot relative to the patella. Next, the osteotomy site is marked along its medial border, and tapered anteriorly at the distal aspect.
In the remainder of the video, the orientation of the video is switched so that the proximal aspect of the leg is to the left of the screen. A sagittal saw is used to perform the tibial tubercle osteotomy. In this case we used a 55° oblique cut in order to preferentially anteriorize the tubercle and decrease patellar contact forces proximally.
By varying the cut angle and extent of anteriorization, a variety of medialization distances can be achieved. When more anteriorization is required, the slope may be increased, and when more medialization is required, the slope may be decreased.
At the proximal aspect of the osteotomy, the saw blade is taken ¾ of the way across the bone. As the osteotomy cut is performed distally, the cut angle is decreased to taper the cut toward the anterior cortex, and the lateral cortex is breached no further proximally than just past the distal pilot hole to help decrease fracture risk. A periosteal hinge may be left intact on the distal lateral aspect of the cut if distalization is not to be performed.
Then, a 13-mm osteotome is used to make a transverse cut on the anterior tibia proximal to the patellar tendon insertion. Next, the lateral osteotomy cut is finalized at its proximal aspect using the osteotome. The remaining lateral cortex splits like a block of wood connecting the proximal and distal cuts and avoiding the need to strip the anterior compartment musculature for visualization.
After the osteotomy is completed, the tubercle is mobilized. It is important to recognize that with this technique, the anterior compartment and fascia remain intact and attached to the shingle of bone.
The amount of medialization is measured and corrected relative to the preoperative TT-TG distance in order to confirm normalization to within a range of 6 to 10 mm. In this case, medialization of 11 mm was used, and an 11-mm osteotome was used to confirm proper amount of correction. A towel clip is used to secure the shingle of bone into its new position.
The posterior cortex underlying the pilot holes is then drilled perpendicularly through the tuberosity fragment. A 3.2-mm drill is used to create a third, more obliquely oriented hole in order to ultimately place an additional screw off axis from the other 2 in case a fracture propagates between the other 2 screws.
The drill bits are left in place to maintain points of fixation while screws are inserted. After the screw length is measured and the bone is tapped, the first 4.5-mm, fully threaded, cortical screw is inserted. Screw insertion is begun using a drill, however, the final 20% of tapping and screw insertion should be performed by hand to prevent iatrogenic fracture if the tip is off axis with the posterior cortical hole.
A second and third screw are placed in the same manner. A finger should be applied to the shingle to detect if it lifts off during tapping and screw entry, which indicates that you are off axis with the posterior cortical hole and could potentially cause a fracture. Here, the third and final screw is placed off axis to secure fixation in case of fracture propagation between the first and second screws.
The final fixation construct is then evaluated using fluoroscopy to ensure bicortical fixation is achieved and screws are an appropriate length. Dynamic clinical evaluation is then performed. In this patient, a lateral Z-lengthening was also performed, but discussion of this is outside the scope of this video.
Cancellous allograft bone chips are then added to the osseous defect before standard closure is performed.
Some of the more notable potential complications of a tibial tubercle osteotomy are listed here and include nonunion or malunion, fracture, instrumentation failure, neurovascular injury, arthrofibrosis, and symptomatic hardware.
We restrict patients to 50% weightbearing in a hinged knee brace for the first 6 weeks after surgery. The brace is locked to prevent flexion beyond 70° for the first 2 weeks postoperatively, but this is liberalized to 90° afterwards, and then range of motion restrictions are removed after week 4. We allow patients to return to sport after 19 to 24 weeks postoperatively, provided they have completed a sport-specific return to play protocol.
Tibial tubercle osteotomy is a well-validated treatment option for several different patellofemoral joint conditions, including patellofemoral instability and chondromalacia. Biomechanical studies have established the effects of an anteromedializing tibial tubercle osteotomy on decreasing patellar contact pressures laterally and centrally, which may relieve pain in patients with chondromalacia predominantly affecting these areas. 1
Bellemans et al 2 evaluated 29 patients with chronic knee pain, who underwent anteromedial tibial tubercle transfers and found significant improvements in mean Lysholm (62 preoperatively, 92 postoperatively) and Kujala scores (43 preoperatively, 89 postoperatively) at mean follow-up time of 32 months. Long-term results have also demonstrated durability. 4
Buuck and Fulkerson 3 reported the results of anteromedializing tibial tubercle osteotomy in 42 knees at an average of 8.2 years of follow-up. In all, 86% of patients achieved good or excellent results, and 81% of patients returned to sports following surgery. Finally, a systematic review by Saltzman et al, 7 which included outcomes of 21 tibial tubercle osteotomy studies and more than 1000 knees found that postoperatively patients had significantly improved knee pain and functional outcome scores.
From the Department of Orthopedic Surgery at the University of Virginia, we thank you for watching.
Our references are listed here.
Footnotes
Submitted June 27, 2021; accepted August 23, 2021.
One or more of the authors has declared the following potential conflict of interest or source of funding: D.R.D. receives institutional grant and research support from Zimmer, Aesculap, and Moximed; is a paid consultant for Depuy Mitek; and receives royalties from Smith and Nephew. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
