C. S. Goldthorpe, R. Schwartz
We report here a young, physically active law enforcement officer who presented to our office with bilateral knee pain secondary to severe genu valgum with osteoarthritis. This case illustrates the dilemma of deformity correction, future total knee arthroplasty (TKA), and preserving an active life style.
A 32-year-old male presented to our Orthopedic clinic with bilateral knee pain that was gradually getting worse over the course of 10 years. He is an active law enforcement officer who works in the field but has noticed more difficultly performing his normal duties at work secondary to bilateral knee pain, left worse than right. Seventeen years prior, at the age of 15, he had a left ACL tear due to a football injury. Subsequently, he underwent an ACL reconstruction by another provider. To the patient’s knowledge the procedure was without complication and he returned back to normal life. Unfortunately, no perioperative records were available for the ACL reconstruction. Therefore, it’s not known if other associated injuries were present at the time. The patient mentioned for as long as he could remember he had the appearance of “knocked knees.” The patient didn’t have any significant medical history and didn’t take any medications other than anti-inflammatories as needed for knee pain.
Most of the patient’s symptoms were lateral sided knee pain, left worse than right. He denied any significant mechanical symptoms such as locking or instability. There was an obvious valgus alignment of both knees with a medial thrust while ambulating. Surgical incisions were present on left knee consistent with an ACL reconstruction. Lateral joint line tenderness was present. Laxity was present while stressing the MCL at 30 degrees of flexion but had a firm endpoint with the left slightly more noticeable. Negative test included anterior and posterior drawer, Lachman’s, varus stressing, and McMurray’s. Pivot shift wasn’t tolerated. Noticeable crepitus was present with passive and active range of motion.
Radiographs showed bilateral valgus alignment with the mechanical axis line (MAL), also known as Maquet’s line, lateral to the knee. Osteophytes, sclerosis, and joint space narrowing were all present. Some cystic changes were noted on the left knee potentially where the ACL graft was. The mechanical femorotibial angle (MFTA) and the mechanical lateral distal femoral angle (mLDFA) were measured (figures 1,2).
Figure 1 – Preoperative Images
Pre-operative full-length alignment radiographs were taken. (A) is the right single leg standing mLDFA measuring 76.1 degrees. (B) is the right single leg standing MFTA measuring 17.4 degrees. (C) is bilateral MFTA with the medial part of the knees having complete contact and preventing a true measurement of MFTA. (D) is the left single leg standing MFTA measuring 26.1 degrees. (E) is the left single leg standing mLDFA measuring 77.8 degrees. Single leg stance gives a true look at the MFTA as the contralateral knee doesn’t impede its deformity.
Figure 2 – Preoperative Images
Full-length alignment films were taken with the Maquet’s line or mechanical axis line drawn (MAL) drawn. (A) Maquet’s line drawn on the right single leg standing. (B) Maquet’s line drawn bilateral with the medial knees touching preventing a true measurement. (C) Maquet’s line drawn on the left single leg standing. Single leg films show a true look at the extent of the deformity.
Non-operative treatment options were discussed including lifestyle changes such as change in job duties, varus producing knee braces, continuing anti-inflammatories, steroid injections, hyaluronic acid injections. He was already beginning to modifying his daily activities to accommodate his symptoms. Anti-inflammatories were already a part of his normal regimen. Due to the advanced skeletal malalignment and arthritis, hyaluronic acid injections were also avoided. Steroid injections were avoided to prevent perioperative infection risk as patient was indicated for surgical treatment.
Bilateral distal femoral osteotomies (DFO) were planned. Due to the large correction needed to off load the lateral compartments of the knees, a step-cut, single plane rotational osteotomies were planned (figure 3).
Figure 3 – Preoperative Planning
Using Saw Bones, a preoperative plan was practiced. (A) lateral view of distal metadiaphysis of the femur showing the frontal plane cut 6 cm in length and the hemiaxial cuts planned. Actual intraoperative cuts in the hemiaxial plane were reversed compared to these images to minimize risk of neurovascular injuries. (B) view from the anterior distal femur showing a Steinmen pin as the axis of rotation and preventing translation. (C) lateral view of distal femur after correction made.
Operatively, both legs were prepped. Two surgical teams worked simultaneously. There were no preoperative CT scans or fabricated 3D printed guides. A distal femur lateral approach was used. Vastus lateralis was elevated off lateral intermuscular septum and retracted anterior for exposure. 6 cm proximal to the knee joint marked the distal extent of the osteotomy. The length of the frontal plane osteotomy was 6 cm. Distally, the hemiaxial cut exited anteriorly; proximally the cut exited posterior. This was to minimize the risk of neurovascular injury. A Steinmen pin was used in the center of the osteotomy from anterior to posterior to prevent the medial, lateral, proximal, and distal translation of the bone cuts but allowed coronal plane rotation which our correction pivoted around. Overall, correction was measured and determined by intraoperative mechanical alignment of the leg from center hip to center ankle. Bovie cord was used to visualize this mechanical axis under fluoroscopy.
Once the mechanical axes crossed slightly into the medial tibial plateau (60% of the distance from lateral to medial tibial plateau), a second Steinmen pin was used from anterior to posterior (AP) to now secure frontal plane rotation. Sequentially, these pins were replaced with two 4.5 lag screws to provide compression. Lateral distal femur locking plates were used with 4.5 locking screws (figures 4, 5, 6).
Figure 4 – Intraoperative images
Intraoperative images were taken. (A) exam under anesthesia was preformed showing a left knee valgus stress accentuating the deformity. (B)
after coronal plane rotation within the osteotomy there was a small overhang of bone which was removed with a saw.
Figure 5 – Post-operative Week 2
Post-operative nonweight bearing distal femur radiographs at two weeks showing no hardware complications or any changes from intraoperative images.
Postoperatively, knee immobilizers were used. Patient was non weight bearing for four weeks. At two weeks, active range of motion was initiated and immobilizers were discontinued while in bed.
Figure 6 – Post Operative Week
Post-operative nonweight bearing AP knee radiographs at 2 weeks.
At four weeks, patient was allowed to weight bear only for transfers with the help of a walker. At six weeks weight bearing as tolerated was allowed.
There were no adverse events or major complications. However, at approximately six weeks postoperatively, active and passive range of motion stopped progressing which measured on the left: 45 and 50 degrees of knee flexion with active and passive respectively. The right knee measured 50 and 55 degrees of active and passive knee flexion respectively.
Patient was scheduled for manipulation under anesthesia at six weeks postoperatively. Intraoperatively, after careful manipulation, flexion on the left was 115 degrees passive and on the right was 130 degrees passive.
Three months postoperatively he was tolerating full-weight bearing with a normal gait. Active range of motion was 105 and 110 degrees on the left and right respectively. Patient return to work eight hour per day on a sedentary work restriction. Physical therapy continued. Radiographs showed bony union and no hardware complications (figure 7, 8, 9).
Figure 7 – Post Operative Week 12
Post-operative weight bearing AP knee radiographs at three months which shows callus and the beginning of remodeling.
Figure 8 – Post Operative Week 12
Post-operative weight bearing lateral knee radiographs at three months.
Figure 9 – Post Operative Week 12
Post-operative sunrise knee radiographs at three months.
Four months postoperatively, active range of motion was 120 degrees bilateral. He continues to progress and has begun work specific physical therapy exercise specific to being a law enforcement officer. Discomfort is only present with physical therapy activities. Gait is normal without discomfort. Standing full-length alignment films showed bony union and some remodeling. Right knee had residual valgus of 7.2 degrees and left was within the target varus range of 3.1 degrees (figure 10).
Figure 10-4 Months Post- operative
Post-operative standing full-length alignment films at four months. (A) MAL on the right shows small residual valgus as line passes through lateral plateau. Left MAL passes through medial plateau as knee is now in slight varus. (B) MFTA on right measures 7.2 degrees of valgus and on the left 3.1 degrees of varus.
Common document procedures for valgus knee deformity correction include medial closing and lateral opening wedge distal femoral osteotomies. If the correction needed is small then a high tibial medial closing wedge osteotomy could be used. However, there aren’t any good recommendations on how to approach a significant deformity such as the patient presented in this case study. High tibial medial closing wedge osteotomies that correct more than 10 degrees may cause lateral tibia subluxation. High tibial lateral open wedge osteotomy in such patients would potentially cause negative alerted mechanics and an elevated joint line with subsequent patella baja.1 Faiz et al reported on patient outcomes that have undergone a DFO with deformity corrections less than 10 degrees. Their complication rate was 4.7% with a probability survival rate of 89% at 10 years.2
Complications have been reported by Ramanathan et al with distal femoral osteotomies including hardware pain (20.5%), arthrofibrosis (12.8%), hardware failure (3.8%), septic arthritis (3.8%), and nonunion (2.6%). These authors also stated there was a 10-year survival rate of 78%.3
Out of concern for large corrections needed (over 17 and 26 degrees for right and left knee respectively) in this patient a new, not yet described osteotomy was pursued out of concern for delayed union, nonunion, large amounts of bone graft needed and its associated morbidity. The step-cut rotational osteotomy was used because of its large surface area for bony contact, distribution of forces, and availability for compression with hardware all leading to a more predictable union without the need of bone graft. Other researchers have documented success for step-cut osteotomies, done for various reasons, in other areas with excellent outcomes such as the ulna and the first metatarsal4.
A distal femoral, step-cut, rotational osteotomy may be an additional good operative technique in patients with a significant valgus deformity with a needed correction over 20 degrees. This case demonstrated reliable healing without the need for bone graft while prolonging the need for a knee arthroplasty in a severe case of bilateral genu valgum in a young patient.
- Puddu G, Cipolla M, Cerullo G et Which Osteotomy for a Valgus Knee? International Orthopaedics, April 2010 34:239-247 doi: 10.1007/s00264-009-0820-3
- Shivji F, Foster A, Risebury M, et Ten-year survival rate of 98% after Distal Femoral Osteotomy Surgery for Lateral Compartment Osteoarthritis of the Knee. Knee Surgery, Sports Traumatology, Arthroscopy, April 2020. doi: 10.1007/s00167-020-05988-5
- Ramanathan D, Keudell AV, Minas T, Gomoll AH. Survivorship and Complications of the Distal Femoral Osteotomy. The Orthopedic Journal of Sports Medicine, July 2014 Supplement 2; 2(7): 1-2p doi: 10.1177/2325967114S00051
- Papatheodorou L, Baratz M, Bougioukli S et Long-Term Outcome of Step-Cut Ulnar Shortening Osteotomy for Ulnar Impaction Syndrome. The Journal of Bone and Joint, American Volume, November 2016; 98(21):1814-1820. doi: 10.2106/JBJS.01111