case_images: PMC6742866_01
case_images: Antero-posterior (a) and lateral view (b) of the right knee showing enthesial spurs at the site of quadriceps expansion on the patella, ossification of collateral ligaments along with minimal tibiofemoral arthritis.
case_images: JOCR-9-34-g001.jpg
case_images: PMC6742866_01_JOCR-9-34-g001.jpg
case_images: F1
case_images: There were unusual spike shaped enthesophytes in the quadriceps tendon (Fig. 1).
case_images: Lateral view of cervical and thoracic vertebra (a and b) showing flowing wax appearance of osteophytes. Lateral view lumbar-sacral spine (c) showing consecutive calcification of spinous ligaments with preservation of intervertebral disc height.
case_images: JOCR-9-34-g002.jpg
case_images: PMC6742866_01_JOCR-9-34-g002.jpg
case_images: F2
case_images: On further evaluation of his spine, there was classical ossification of the anterior longitudinal ligament of thoracic, cervical, and lumbar regions with the maintenance of joint space (Fig. 2).
case_images: Antero-posterior view of pelvis with both hips showing pelvic whiskering, normal hip joint space, preserved sacroiliac joint, ossification of the labrum, and capsule.
case_images: JOCR-9-34-g003.jpg
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case_images: F3
case_images: Pelvis skiagram showed ossification of the capsule with maintenance of joint space (Fig. 3).
case_images: Anteroposterior (a) and oblique view (b) of foot showing Achillestendon spurs and ossification of capsule around intertarsal and metatarsophalangeal joints.
case_images: JOCR-9-34-g004.jpg
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case_images: F4
case_images: Small joints of hand and feet also showed ossification in the ligaments and joint capsule (Fig. 4).
case_images: Intraoperative navigation image showing sagittal and coronal deformity. Purple dots represent kinematics of the knee along with range of movement.
case_images: JOCR-9-34-g006.jpg
case_images: PMC6742866_01_JOCR-9-34-g006.jpg
case_images: F5
case_images: All knee replacements in our unit are performed with image-free Ci navigation system (Brain Lab, Munich, Germany) with pins inserted inside the incision (Fig. 5).
case_images: Intraoperative navigation image showing additional +4mm distal femur resection.
case_images: JOCR-9-34-g007.jpg
case_images: PMC6742866_01_JOCR-9-34-g007.jpg
case_images: F6
case_images: We then went back and resected 4 mm more of the distal femur, but still had a tight extension and flexion gaps (Fig. 6). We finally had to resect 4 mm more of tibia to get to equal flexion and extension space (Fig. 6) and correction of sagittal deformity up to 5 o (Fig. 7).
case_images: Post-operative anteroposterior (a) and lateral X-rays (b) of the knee.
case_images: JOCR-9-34-g009.jpg
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case_images: F8
case_images: The coronal femoral angle was corrected from 86.4  to 90.1  and the coronal tibial angle corrected from 85  to 89.5  postoperatively (Fig. 8).
case_images: Pre-operative (a) and post-operative (b) full length antero-posterior X-ray of lower limb showing restoration of hipknee- ankle axis.
case_images: JOCR-9-34-g010.jpg
case_images: PMC6742866_01_JOCR-9-34-g010.jpg
case_images: F9
case_images: Hip-Knee-Ankle (HKA) angle improved from 170.5  to179.6  postoperatively (Fig. 9). His knee society score improved from 34 points to 85 points, postoperatively.