Article

Introduction

Successful outcome after a surgical intervention depends not only on the patient’s underlying condition, the surgical procedure and the skill of the surgeon, but also the postoperative care offered. Postoperative care following hip surgery is no exception and is key for successful outcomes. Most cases of hip surgery are performed to treat hip dysplasia (HD), but postoperative care for other causes, such as aseptic necrosis of the femoral head, hip luxation, and fracture of the acetabulum or femoral head or neck, should not be overlooked. This paper will consider rehabilitation options, primarily for HD treatment, but will also review post-operative therapy for other hip-related conditions.

Hip dysplasia surgery 

Rehabilitation following surgery for hip dysplasia is important in order to have the best outcome possible. Some procedures (including juvenile pubic symphysiodesis and double or triple pelvic osteotomy) are performed to preserve the hip joint, while others (including total hip replacement and femoral head and neck excision) are salvage procedures. The type of postoperative care and rehabilitation are specific for each surgical procedure, but weight management and achieving a normal body condition score is important for long-term success in all cases (1).

Pubic symphysiodesis

Pubic symphysiodesis is a relatively simple procedure, but it must be performed prior to 20 weeks of age to have adequate growth of the remaining pelvis to correct mild hip joint conformation (2). In general, dogs do very well with just a few days of restricted activity to allow the incision to heal; there are no implants or other possible sites of failure. The focus of rehabilitation is to promote muscle development of the hind limbs with low-impact exercises, followed by return to normal activity. It is important to realize that any hip laxity will remain until pelvic growth allows improved dorsal acetabular coverage. Therefore, low impact exercise, especially swimming, is recommended until skeletal growth is complete.

Double or triple pelvic osteotomy

A double (DPO) or triple (TPO) pelvic osteotomy may be performed in young dogs with hip joint laxity, clinical signs, and preferably no radiographic osteoarthritis (3). Therefore, these procedures are usually undertaken between 6 and 10 months of age, with surgery involving osteotomies of the ilium, pubis, and ischium (for TPO) with special bone plate fixation (Figure 1). Although young dogs heal relatively quickly, they also tend to be very active. The bones are less dense and complications due to limb overuse too soon after surgery are common, such as screw loosening and fixation failure (3). Therefore, it is important to realize that activity must be severely restricted to leash walks only, with no running, jumping or playing. A sling under the abdomen for the first two weeks is strongly recommended to prevent unwanted weightbearing and stress on the repair, especially when unexpected activities occur, such as jumping or slipping on the floor. Confinement to a crate and good non-slip flooring are essential to help prevent unwanted falls.

Following DPO or TPO, exercise to limit muscle atrophy should be instituted, but as noted above, postoperative activity is restricted to leash walks for 4-6 weeks to allow bone healing. Cryotherapy, NSAIDs, Passive Range of Motion (PROM) and assisted ambulation, followed by controlled, low-impact therapeutic exercises, are indicated. Leash walking, sit-to-stand exercises, and aquatic walking may be useful to attenuate muscle atrophy while avoiding excessive stress on the repair (4). After adequate bone healing has occurred, the focus of rehabilitation is to strengthen muscles of the hindquarters; strengthening activities should parallel bone healing.

Total hip replacement

Total hip replacement (THR) can result in very good use of a limb with hip dysplasia (Figure 2). However, patients are vulnerable to complications in the weeks that follow surgery, requiring skilled care for optimal functional recovery. High-risk patients and living situations must be identified, and confinement and therapy must be adapted to minimize these risk factors. Older dogs generally have more advanced disease (e.g., increased bone remodeling, chronic joint laxity, severe periarticular fibrosis) and comorbidities, and they may be more deconditioned and prone to falls due to weakness. Younger dogs may be unruly, poorly trained, and also prone to falls, this time due to excessive activity.

Recognized complications of THRs include luxations, fractures, neurapraxia, implant loosening, and infection, with the overall complication rate being approximately 10-15% (5). Luxation is the most common short-term complication, with an incidence of 4-8% (5,6), mostly occurring within the first 3 months after surgery. Luxations can occur when the cup and stem contact each other during activities of daily living, a phenomenon named impingement. Traumatic luxations can occur when a patient falls into a splayed posture (ventral luxation) or onto the hip (dorsal luxation), underscoring the need for supported ambulation and measures to prevent slipping or loss of balance. 

Femoral fractures are another complication of THR, occurring both intraoperatively and postoperatively at around 2-5% (5,6). A femur could be at risk of fracture because of thin cortices; a fracture that occurs during surgery can often be stabilized with cerclage wires placed around the femoral shaft. Sciatic nerve neurapraxia is an infrequent complication of THR, and is generally transient, lasting for a few weeks to a few months, but it can be permanent.

Acute or chronic infections can also occur after THR, most being low-grade infections developing weeks to months post-surgery. Infection should be suspected in patients that exhibit progressively poorer limb use in the absence of radiographic evidence of fracture or implant loosening. Stems or cups used in THR can become loose, either because of lack of bone ingrowth into cementless implants, or because of aseptic loosening over time. The bone ingrowth that occurs in the first 6-8 weeks after surgery is critical to long-term prosthesis stability, so excessive activity during this time causes a disruption of healing, poor limb use and progressive loss of muscle mass.

The hospitalized rehabilitation environment is ideally suited for patients who are recovering from THR. However, some facilities are not equipped for continuous care, so most patients are discharged to home care. It is critical for clinicians to coordinate client education and communication regarding housing modifications, activity restrictions, and home rehabilitation care for patients recovering from surgery. The decision for outpatient rehabilitation at the clinic must be carefully considered. Although this can be beneficial, transport of the patient to and from the rehabilitation center is not without risk, considering the potential for injury while in the vehicle or getting in and out of it. Fortunately, much of the initial postoperative care may be provided by the owner until transporting the patient is less risky, approximately one month after surgery. In addition, most dogs are performing at or above presurgical levels within 3 months of surgery with minimal rehabilitation (7).

Rehabilitation goals include controlling postoperative pain, minimizing complications, increasing and restoring function, restoring Passive Range of Motion (PROM) and Active Range of Motion (AROM), increasing strength of the surrounding musculature, and improving the patient’s quality of life. Rehabilitation after THR generally takes 3 months, but adherence to an individualized home exercise program may be warranted for longer, depending on each patient’s needs. Most soft tissue healing, including the joint capsule, takes place during the first month, with maturation continuing for months beyond that point. The bone-implant interface of cemented implants reaches maximal strength one day after surgery, whereas the bone-implant interface of cementless implants relies on bone ingrowth. Most of the ingrowth occurs during the first 2 months; afterward, bone remodels slowly during the first year after surgery. Many patients use their operated limb consistently by the end of the first month, walk without lameness by the end of the second month, and can engage in additional activities by the end of the third month. These timelines serve to guide rehabilitation and patient activity levels to avoid complications. A support sling should be used whenever standing and walking during the first two weeks to help prevent falls. Dogs should be confined to a small area when unsupervised and should have good non-slip floor surfaces to walk on. In some cases there is restricted hip extension, and here it is important to provide gentle sagittal plane ROM and stretching exercises to help improve hip mobility (4).

In the initial postoperative period NSAIDs, cryotherapy, and gentle PROM are indicated (8). Dogs are restricted to leash walking, with no running or jumping for the first 3 postoperative months. Initially, supported sling walks are performed for 5 minutes, 3-5 times daily. After the dog is walking confidently, typically 2-3 weeks after surgery, leash walks can progressively increase. Subjectively, most patients can walk for 10-15 minutes several times daily without lameness by the end of the first month after surgery, 15-20 minutes several times daily by the end of the second month, and 30 minutes twice daily by the end of the third month. Muscle strengthening can be achieved using controlled walking, treadmill activity and sit-to-stand exercises, with the duration of these activities gradually increased during the first 2 months. Balance and proprioception re-education may also be important, using inflatable balance discs or boards. Dogs experiencing complications following THR have additional rehabilitation needs.

Femoral head and neck surgery

Femoral head and neck ostectomy (FHO) may be performed as a salvage procedure to improve pain in dogs with severe HD if total hip replacement is not an option (9). It is critical that the excision be performed correctly, with complete removal of the head and neck with no sharp bone edges remaining (Figure 3). The pseudoarthrosis should be subjected to a ROM assessment to check for any bone-on-bone contact or excessive crepitus; if detected, revision surgery may be necessary. Rehabilitation following FHO is critical yet challenging, because these patients are often painful and success hinges on excellent pain control and early return to function (10). Adequate analgesia throughout the rehabilitation program is a key factor for a successful outcome, and opioids may be combined with NSAIDs for pain control immediately after surgery. This is very important to help limit reflex inhibition and encourage early limb use; ROM and stretching are essential, especially in extension (8). Cryotherapy can help reduce pain and early inflammation, and is initiated immediately after surgery with the hip slowly placed through continuous full ROM while the dog is recovering from anesthesia (Box 1). Massage may also be helpful before passive or active exercises. Early limb use should be encouraged; for dogs that are reluctant to use the limb, weight-shifting activities (Figure 4) and a syringe cap placed under the contralateral foot are useful to help encourage weightbearing.

Box 1. Example treatment plan for a dog with HD treated by FHO.

Rehabilitation after FHO should emphasize regaining active hip extension. In addition to PROM for hip extension (Figure 5), ground treadmill or underwater treadmill exercises (after suture removal) may be used to promote active hip motion (8). Walking in an underwater treadmill may promote more functional activity if the water level is at the stifle or lower, and an inclined treadmill may also help, although the inclination may need to be greater than 5% to induce much increase in hip ROM (Figure 6). Sit-to-stand exercises may be introduced soon after surgery to strengthen hindlimb muscles, without encountering the pain associated with full hip extension. Walking up hills or steps can then be initiated to promote hip extension and improve muscle strength after the animal is ambulating well. Dancing exercises encourage muscle strengthening and hip extension, especially dancing backwards, but this should be reserved until walking with minimal lameness. Although swimming is a good conditioning exercise, it does not promote hip extension. Cryotherapy may be used at the end of each therapy session to reduce inflammation. Most animals will toe-touch consistently within 1-2 weeks, partially weight-bear in 3 weeks, and be actively using the leg by 4 weeks. The animal should regain good walking and trotting gaits, but hip extension is often limited (11). Prognosis for return to daily function is generally good but varies with the surgical technique and the chronicity of the pre-existing lameness. Large dogs may have a less satisfactory result than smaller animals, and adherence to the advised program may also affect the outcome, so it is important to manage pain to allow appropriate rehabilitation.

Aseptic necrosis of the femoral head

Aseptic necrosis of the femoral head (Legg-Calve-Perthes disease) may occur in small breed dogs that are less than a year of age. Dogs with this condition are usually quite lame and painful, necessitating a salvage procedure, and although THR is possible in small dogs, FHO is generally the treatment of choice. Rehabilitation should be performed as described for hip dysplasia.

Hip luxation

Most traumatic hip luxations occur in a craniodorsal direction. The luxation may be treated with closed reduction or open surgical reduction and stabilization, with closed reduction successful in approximately 50% of cases if the hip is relatively stable immediately after reduction. A non-weightbearing sling, such as an Ehmer sling, is placed for two weeks after closed reduction. During this time exercise is severely restricted. Following removal of the sling and confirmation that the hip is still reduced, very gentle flexion and extension exercises may begin with 10-15 repetitions twice daily, avoiding adduction and external rotation movements. Slow leash walks may be instituted, 5 minutes per session, with 3-5 sessions per day during the first week. If the lameness is resolving, the length of walks may be increased by 5 minutes per week. After 4-6 weeks patients may gradually return to normal activity if lameness has resolved.

Alternatively, surgical reduction may be performed with a capsulorrhaphy, toggle pin, prosthetic capsule, anti-rotational suture, or triple pelvic osteotomy procedure(s). A non-weightbearing sling may or may not be placed post-surgery. ROM can be done in a sagittal plane only, with no weight-bearing torsional exercises performed (e.g., circles or figure-of-eight) until 4-5 weeks after surgery. Slow, short leash walks may be introduced when the patient is able, as well as weight-shifting activities. Alternatively, some dogs are treated with FHO and rehabilitation is performed as previously described. Closed or surgical reduction is contraindicated in dogs with hip luxation secondary to severe osteoarthritis (Figure 2), and THR or FHO is indicated in this situation. 

Fracture of the acetabulum or femoral head/neck

Fractures of the acetabulum, capital femoral physeal fractures, or femoral neck fractures may occur, and rehabilitation in these cases may be challenging. Primary repair with plates, screws and pins may be performed, but when planning the postoperative care consideration must be given to stability of the repair. In general, an approach similar to that for hip luxation rehabilitation may be undertaken. In some cases, FHO may be performed, and the postoperative care is the same as for hip dysplasia, but keep in mind that recovery after FHO due to trauma in a previously normal hip is usually prolonged, because there is no fibrosis of the joint capsule to start a pseudoarthrosis. 

Conclusion 

Rehabilitation following hip joint surgery is vital to regain acceptable function of the affected limb. It is especially important to begin rehabilitation as soon as possible after femoral head and neck osteotomy to attain near-normal ROM and weight bearing. A more conservative approach should be taken with total hip replacement. Rehabilitation following trauma to the hip is also important, and the type of activity undertaken depends on the stability of the repair, but progressive exercise challenges are regularly made as the patient improves. 

References

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