Femoral Head and Neck Ostectomy

Canine Hip Dysplasia (CHD) is a developmental condition that begins as dogs grow, leading to instability or a loose fit (laxity) of the hip joint (Figure 1). This laxity is responsible for possible clinical signs such as hip pain, impaired limb function, and progressively worsening joint changes. The hip is a ball-and-socket joint, and repeated abnormal motion of the femoral head (the “ball”) gradually deforms the acetabulum (the “socket”). Over time, the long-term consequence of laxity is progressive cartilage loss, formation of scar tissue around the joint, and development of osteophytes (bone spurs) at the ball and socket (Figure 2).

CHD arises from multiple contributing factors, but heredity (genetics) is the single most important risk factor. Rapid weight gain and accelerated growth from excessive caloric intake can worsen the development of CHD. Hip dysplasia is seen most frequently in large-breed dogs.

Figure 1. Hip dysplasia appears as hip joint instability. As the dog bears weight, the femoral head (thigh bone “ball”) shifts abnormally relative to the acetabulum (hip “socket”).

Figure 2. Joint instability causes abnormal cartilage wear. This cartilage damage results in bone spur formation and scar tissue, which are characteristic findings of hip arthritis.

Signs of CHD include lameness (limping), reluctance to stand up or jump, shifting body weight forward onto the front legs, reduced muscle mass in the hind limbs, and pain in the hips. Dogs with CHD are commonly divided into two symptomatic groups:

• Group 1: younger dogs without arthritis but with marked hip laxity
• Group 2: older/more mature dogs that have developed hip arthritis secondary to CHD

Dogs may show signs at any point during disease development, although many dogs with CHD have no obvious symptoms.

Figure 3. Hip radiograph showing hip arthritis resulting from hip dysplasia.

CHD is diagnosed using a combination of two approaches. Specially positioned hip radiographs and specific palpation techniques used to assess abnormal hip laxity typically require light sedation.

The most accurate radiographic method for early-age assessment is the PennHIP distraction technique. This is a quantitative test that measures the true amount of hip laxity. It can accurately predict whether a puppy is likely to develop hip dysplasia and helps determine which preventive surgical options are most appropriate to reduce the risk of disabling arthritis (Figure 3). Performing PennHIP requires specialized training and equipment. PennHIP also provides an independent written confirmation of CHD for both the owner and the evaluating veterinarian. Some primary care veterinarians, and many ACVS board-certified veterinary surgeons, have completed the training and possess the necessary equipment to perform this test.

The palpation-based method is the Ortolani Sign. It has been used in human newborns since 1937 and remains the “gold standard” worldwide for early hip dysplasia diagnosis in newborn infants. In puppies, it has been used since 1985 under light sedation. Although it is not quantitative, a positive Ortolani Sign generally indicates that the puppy will usually develop hip arthritis by one year of age. Many primary care veterinarians can perform this exam during early puppy vaccination visits at 10–16 weeks of age. If the Ortolani Sign is negative, false negatives are possible; this uncertainty can be addressed with the quantitative PennHIP method.

Unfortunately, the commonly used radiographic screening method from the Orthopedic Foundation for Animals (OFA)—widely used by breeders—is not accurate for predicting CHD at very young ages. OFA recommends a preliminary evaluation at 1 year and a final evaluation at 2 years. This timing is too late in the disease course because dogs at risk of crippling arthritis may have already missed two preventive surgical options (JPS and DPO/TPO, see Treatment) that can significantly lessen the effects of hip dysplasia by one year of age.

Figure 4. Pelvic radiograph after TPO showing the specialized plate and screws holding the pelvis in a rotated position to improve femoral head coverage by the acetabulum.

Figure 5. Pelvic radiograph after FHO showing absence of the left femoral head (“ball”).

Figure 6. Normal hip (left) and arthritic hip (arrow). Total Hip Replacement can restore normal “ball-and-socket” structure and function using implants (color image).

Early identification of hip laxity is essential to prevent cartilage injury caused by progressive instability.

Treatment Option 1: Juvenile Pubic Symphysiodesis (JPS)

Puppies can be accurately diagnosed with abnormal laxity as early as 10 weeks (see Diagnostics) and treated surgically with Juvenile Pubic Symphysiodesis (JPS). Between 10 and 18 weeks, commonly during vaccination visits, puppies should be examined by a primary care veterinarian or an ACVS board-certified veterinary surgeon to assess whether pathologic laxity is present and could lead to CHD.

A recent evidence-based review of multiple peer-reviewed scientific studies concluded that “JPS surgery is a method of consistently providing normal pain free hip function.” JPS is a minimally invasive procedure that closes a growth plate at the bottom of the pelvis. This alters pelvic growth so that, over the next 4–6 months, the acetabulum increasingly covers the femoral head as the puppy grows. Many patients can go home the same day.

During the 4–6 months of growth after JPS, leash walks are acceptable, but vigorous off-leash activity is discouraged until follow-up examinations at about 10 months confirm pain-free hip function.

Weight control and avoidance of rapid growth should be managed using measured portions of low-protein dry diets (20–21%) for rapidly growing large-breed puppies, starting early and continuing after JPS until 12 months of age.

JPS works by stopping growth of the pubis (part of the pelvis) to reshape pelvic development and increase femoral head coverage, thereby reducing laxity. It is a relatively minor operation but must be performed before 18 weeks of age. Because most puppies at this age do not show symptoms, early diagnosis with examination and specialized radiographs is crucial.

Treatment Option 2: Double or Triple Pelvic Osteotomy (DPO/TPO)

DPO/TPO is intended for immature dogs—ideally under 8–10 months—that have CHD but no radiographic signs of arthritis. These procedures involve cutting the pelvis in two locations (DPO) or three locations (TPO) and rotating the segments to improve acetabular coverage of the femoral head and reduce laxity (Figure 4). TPO has been used successfully for decades in dogs and children. Newer implant technology (locking plates and screws) can achieve similar outcomes with only two bone cuts (DPO), making it less invasive.

The optimal time to detect pathologic laxity is often at the time of spay/neuter, usually between 6–8 months. The primary care veterinarian performing the sterilization may be able to take radiographs and assess laxity by palpation (see Diagnostics). Dogs that already show lameness with early arthritic changes are not ideal candidates for DPO/TPO, and neither are dogs with extremely severe laxity—some puppies may essentially have no functional hip joint by 6 months of age.

Treatment Option 3: Total Hip Replacement (THR)

Total Hip Replacement (THR) is an option for young dogs that are not successfully treatable with JPS or DPO/TPO. These dogs must be medically managed until sufficiently mature for THR—at least 1 year of age. Based on evidence-based medicine from multiple peer-reviewed publications, THR is described as the second surgical method that most consistently provides near-normal, pain-free function for dogs with CHD.

THR addresses hip pain by recreating normal hip mechanics, improving range of motion and limb function. Similar to humans, canine THR replaces both the femoral head and the acetabulum using metal and polyethylene (plastic) implants (Figure 6). Fixation may be achieved with bone cement, metal pegs, or press-fit (bone ingrowth) techniques.

Treatment Option 4: Femoral Head Ostectomy (FHO)

The final surgical option for pain relief from severe laxity/dysplasia is Femoral Head Ostectomy (FHO). This procedure can be performed at any age and may provide sufficient comfort in dogs weighing less than 60–70 lbs, potentially avoiding daily anti-inflammatory medication and its costs and side effects.

FHO may benefit young dogs that do not qualify for JPS or DPO/TPO, or dogs that do not improve adequately with medical management alone. The technique removes the femoral head (“ball”) to reduce pain caused by abnormal joint contact that wears cartilage and by stretching of periarticular soft tissues due to laxity (Figure 5).

After FHO, a “false joint” forms, with surrounding muscles transferring forces from the limb to the pelvis during movement. The goal is pain relief rather than restoration of normal hip mechanics. About two weeks after surgery, controlled exercise is encouraged; anti-inflammatory medication is often given daily during the first 1–2 months, and afterward may be needed only intermittently.

Dogs treated with FHO must stay lean for life and follow a restricted exercise program (leash walks and limited activity in yard/house). They are not suited for athletic work such as hunting, agility, advanced obedience, running with owners, and similar activities. If that level of activity is desired, THR would be required.

Medical Management

This approach depends on multiple variables: age, weight, laxity severity, the owner’s lifestyle, and willingness to assume ongoing medication costs and, in some cases, physical therapy.

Age: Often used for middle-aged to older dogs that are overweight and live relatively sedentary lives.

Weight: All dogs with CHD should be kept very lean from puppyhood through old age. This is the most effective and least expensive long-term way to maintain comfort.

Degree of hip laxity: Severity varies widely. A severely affected puppy with essentially nonfunctional hips by 6 months is likely to experience lifelong daily pain with minimal exercise tolerance. At the other end of the spectrum are dogs with laxity that does not become clinically apparent until middle age; in such cases, cartilage damage progresses more slowly because laxity is less severe.

Lifestyle: Highly active households—or households adding another young active dog or a child—may find the older CHD dog cannot sustain high activity without surgery. No medical plan reliably supports a highly athletic lifestyle comfortably; medical management more realistically corresponds to a lower-impact, sedentary routine.

What medical management involves:

• Maintaining minimal/lean body weight.
• A limited exercise plan, such as leash walks of a length the dog can tolerate comfortably.
• Daily or intermittent (preferable if effective) use of non-steroidal anti-inflammatory drugs (NSAIDs). These can reduce pain substantially, but they may cause important side effects. If used daily, blood tests are needed to monitor for kidney and liver damage. Monitoring frequency depends on the dog’s age and the dose. Long-term therapy should ideally use the lowest daily dose that clearly improves comfort. If the maximum daily dose is required, side-effect risk increases and the combined cost of medication and monitoring can exceed the cost of surgery in young or middle-aged dogs.
• Cartilage-protective supplements are frequently recommended; however, there is no evidence in peer-reviewed literature that they help cartilage repair or protect against wear/damage.
• Animal-derived or fish-oil omega-3 fatty acids as anti-inflammatory support for joints.
• Physical therapy can help dogs with very sedentary routines (e.g., owners away for long hours) because inactivity leads to stiffness. Joint motion and improved muscle strength support comfort and mobility. Physical therapy is also used after CHD surgery to strengthen muscles and speed recovery.

Complication risk after JPS is very low, and most are minor. JPS has high success rates for reducing/eliminating laxity, and aftercare is usually brief—mainly incision care and short-term activity restriction.

Reported complications after DPO/TPO include screw loosening, altered limb range of motion, and narrowing of the pelvic canal. Even so, complication rates are low, and long-term functional outcomes are expected to be good to excellent.

THR offers an excellent chance of markedly improved limb function. Potential THR complications include infection, hip dislocation, gradual implant loosening, nerve injury, and femoral fracture.

After both DPO/TPO and THR, activity should be restricted to leash walks outdoors and confinement to a small indoor area until healing is confirmed by examination and radiographs—generally about 6 weeks for DPO/TPO and 8 weeks for THR. Most dogs bear weight soon after surgery but must be supervised to avoid overuse during healing. If needed, a sling can help during early assisted walking. Dogs should avoid stairs, slippery floors, and rough interactions with other dogs. After the initial restriction period, activity should be increased gradually.

Results after FHO are variable and strongly influenced by patient size and appropriate postoperative rehabilitation. Many dogs retain some degree of lameness, but function should improve compared with preoperative status. After FHO, pets should begin controlled limb use as soon as possible. Intensive rehabilitation and controlled exercise aimed at improving hip range of motion are essential for best results. Some dogs may take up to six weeks or longer after surgery before noticeable improvement occurs.