Patellar fractures in cats with dental anomaly syndrome
Reyes NA, Longley M, Bailey S, Langley-Hobbs SJ. Incidence and types of preceding and subsequent fractures in cats with patellar fracture and dental anomaly syndrome. J Feline Med Surg. 2018 Oct 22
Skull pathology in 10 cats with patellar fracture and dental anomaly syndrome
Howes C, Longley M, Reyes N, Major AC, Gracis M, et al. Skull pathology in 10 cats with patellar fracture and dental anomaly syndrome. J Feline Med Surg. 2018 Sep 10
Patellar Fracture and Dental Anomaly Syndrome (PADS) is a rare but recognized syndrome in cats, formerly colloquially known as “knees and teeth” syndrome. This syndrome is characterized by transverse atraumatic fracture of the patella with concurrent retained deciduous teeth or un-erupted permanent teeth. These retained teeth may result in mandibular or maxillary abnormalities. Cats with this syndrome sustain a patellar fracture at a median of 28 months, with the contralateral patella fracturing within 3 months in more than half of animals. They may also experience non-traumatic fractures to other bones. It is theorized that this syndrome may be caused by an as-yet undescribed primary bone disorder leading to insufficiency fractures.
Two recent papers have attempted to describe features of this poorly understood disease. One paper attempted to describe the incidence and nature of preceding and subsequent fractures in cats with PADS; the other reported the clinical and radiographic orofacial abnormalities in these animals.
Both studies were designed as retrospective case series using the databases of two hospitals dating back to 2005. 191 cats with patellar fractures were included in analysis. Of these 191 cats, 92 (48.4%) had concurrent dental anomalies. 10 cats had mandibular or maxillary anomalies, and 78 (40.8%)has preceding or subsequent fracture to other bones.
The 78 cats with subsequent or preceding fractures had a total of 175 fractures, ranging from 1 to 6 fractures per cat (excluding patellar fractures). 32 cats were male and 41 female, 5 were not recorded. The breakdown of fractures was:
- 53 cats had 90 pelvic fractures
- 28 cats had 39 tibial fractures
- 18 cats had 24 humeral fractures
- 7 cats had 9 calcaneal fractures
- 3 cats each had femoral fracture
- 1 cat each had fractures of the tarsus, sternum, jaw, atlas
Almost all fractures were simple and transverse. All cats had sclerosis visible on either side of the fracture, with some cats showing generalized increases in bone density. 11% of cats with patella fractures had another fracture preceding them, and 41% had fractures after the patella fracture.
The authors conclude that the appearance of the fractures in PADS is most consistent with insufficiency fractures. Patellar fractures are most commonly the first to occur, but in ~10% of cases there is a preceding fracture.
One major drawback to this study was that not all cats had evidence of dental anomalies present. This means that a portion of the cases may not have been PADS, but simply cats with patellar and other fractures. It is also possible, as the authors suggest, that a portion of cats without recognized dental anomalies may have had undiagnosed anomalies, as they may be difficult to detect without intra-oral radiographs, CT or other advanced imaging.
Of the initial 191 cats, 10 were identified that had mandibular or maxillary anomalies in addition to retained deciduous or un-erupted permanent teeth. Clinical history, skull radiographs/CT scans, and microbiology and histopathology (when available) were evaluated by a board-certified dentist and radiologist.
Of the ten cats, two were male and eight female. Nine cats had retained deciduous teeth, one was unknown. Five had unilateral patella fractures and five were bilateral. Fractures to the tibia, pelvis, humerus, calcaneous, femur, and ribs were also present.
Three of the cats were diagnosed with proliferative/reactive bone lesions. One had a suspected mandibular osteoma. The remaining 6 were all affected by osteomyelitis of some description, with some having concurrent abscessation, osteonecrosis, and in one case suspected osteopetrosis. These cats were treated with some combination of surgical debridement/removal, antibiotics, and supportive care. Five of the cats were euthanized for symptoms related to PADS, either the oral or fracture-related manifestations.
The authors conclude that significant oral abnormalities are seen in a portion of cats with PADS. These may be related to the retained decisions teeth or may be due to underlying bone issues. These may appear aggressive radiographically and may be interpreted as neoplastic disease. Cats with PADS should have retained or un-erupted teeth extracted and debridement of proliferative and necrotic bone.
The authors of these two studies have detailed a large amount of information related to PADS. While this disease is considered rare, it is also likely it is underdiagnosed, and so further information helps to understand the nature and course of the disease. While the retrospective nature of the manuscript is less than ideal, it is sufficient for a descriptive study. Further work is needed to determine the physiologic and genetic causes of this syndrome, and to determine if treatment or prevention.
- Langley-Hobbs S. Patella fracture in cats with persistent deciduous teeth Knees and Teeth Syndrome (KaTS). Comp Anim 2016; 21: 620–626.
- Langley-Hobbs SJ. Survey of 52 fractures of the patella in 34 cats. Vet Rec 2009; 164: 80–86.
- Langley-Hobbs S, Ball S and McKee M. Transverse stress fractures of the proximal tibia in 10 cats with non-union patellar fractures. Vet Rec 2009; 164: 425–430