# Luxating Patella in Small Dogs: Grading, Therapy vs Surgical Correction ## Key Takeaways - Patellar luxation in small dogs is graded I-IV based on the ease of luxation and reduction, with Grades III and IV almost always requiring surgical intervention due to persistent lameness and risk of chronic pain and arthritis. - Diagnosis relies on physical palpation to grade the luxation and radiographs to assess trochlear groove depth, tibial tuberosity position, and the presence of osteoarthritis, which is a common sequela. - Conservative therapy (weight management, physical therapy, NSAIDs) is indicated for Grade I and mild, intermittent Grade II luxations, but it does not correct the underlying anatomical deformity. - Surgical correction aims to realign the quadriceps extensor mechanism through techniques like trochleoplasty (deepening the groove), tibial tuberosity transposition (realigning the pull), and soft tissue imbrication. - Concurrent cranial cruciate ligament (CCL) rupture is common (up to 40% of MPL cases) and often necessitates combined surgical approaches such as TPLO and tibial tuberosity transposition for optimal limb function. - Post-surgical care involves strict rest for 4-6 weeks, pain management, and a structured rehabilitation program, with a generally good to excellent prognosis (80-95% favorable outcomes) for surgically treated cases. --- A luxating patella, or a kneecap that slips out of its normal groove, is one of the most common orthopedic conditions seen in small-breed dogs. If your [dog](/knowledge/veterinary-medicine/clinical-methods/dog) is suddenly skipping on a hind leg or holding it up, this condition is often the culprit. This article provides a definitive, evidence-based overview of how veterinarians grade this condition and how they decide between conservative therapy and surgical correction. The decision between managing a luxating patella medically versus surgically is not arbitrary. It hinges on the **grade of the luxation**, the dog's age, the presence of pain, and the impact on the dog's quality of life. While low-grade luxations (Grade I and some Grade II) may be managed with physical therapy and anti-inflammatories, higher grades (Grade III and IV) almost always require surgical realignment to prevent chronic pain and arthritis. This guide will walk you through the entire process, from diagnosis to long-term prognosis, so you can make informed decisions in partnership with your veterinary surgeon. ## Understanding the Canine Stifle: Anatomy of the Patella To understand a luxating patella, you must first understand the anatomy of the "stifle" (the dog's knee). The patella (kneecap) is a sesamoid bone that sits within the tendon of the quadriceps muscle group. It slides up and down within a groove on the front of the femur called the **femoral trochlea**. This mechanism, known as the quadriceps extensor mechanism, is essential for extending the knee and bearing weight. The stability of the patella depends on the alignment of several structures: - The depth of the femoral trochlear groove. - The alignment of the quadriceps muscle pull. - The position of the tibial tuberosity (the bump on the shin bone where the patellar ligament attaches). - The integrity of the joint capsule and surrounding soft tissues. When these structures are misaligned, the patella can slip out of the groove, usually towards the inside of the knee (medial luxation), which is the most common direction in small breeds [1]. Less commonly, it can slip towards the outside (lateral luxation) [2]. In rare cases, it can luxate in both directions (bidirectional luxation) [3]. ## What Causes Patellar Luxation in Small Dogs? Most cases of medial patellar luxation (MPL) in small-breed dogs are considered **developmental** or congenital. This means the dog is born with a subtle conformational abnormality that worsens as it grows. The primary underlying issue is often a complex misalignment of the entire hind limb, not just the knee. This can include: - A shallow trochlear groove. - A misaligned quadriceps muscle pull. - An abnormally positioned tibial tuberosity [4]. - Femoral or tibial deformities, such as a bowed femur [5]. Trauma can also cause a patellar luxation, but this is less common. Regardless of the cause, the result is a biomechanical failure that leads to lameness and, eventually, osteoarthritis. ## Grading the Luxation: The Putnam and Singleton System Veterinarians use a standardized grading system, typically from I to IV, to classify the severity of a patellar luxation. This grading is the single most important factor in determining whether therapy or surgery is recommended. It is based on physical examination findings, specifically how easily the patella can be luxated and whether it stays out. Here is the breakdown of the grading system: - **Grade I:** The patella can be manually luxated (pushed out of the groove) during examination, but it immediately returns to its normal position on its own. Dogs with Grade I luxations are usually asymptomatic and show no lameness. - **Grade II:** The patella spontaneously luxates out of the groove during normal activity, causing a "skipping" lameness. It often returns to the groove on its own, or the dog will shake its leg to pop it back into place. This is the most common grade seen in clinical practice. - **Grade III:** The patella is luxated most of the time. It can be manually pushed back into the groove (reduced), but it will quickly luxate again once released. Dogs with Grade III luxations often have a persistent, noticeable lameness and may carry the leg. - **Grade IV:** The patella is permanently luxated and cannot be manually reduced. This is a severe deformity, and the dog often has a significant, chronic lameness, a bow-legged or knock-kneed stance, and may hold the leg in a flexed position. This grading system is crucial. A Grade I or II luxation may be managed conservatively, while Grade III and IV luxations are almost always surgical cases [6][7]. ## Clinical Presentation: What Does It Look Like? The clinical signs of a luxating patella vary depending on the grade. - **Grade I:** Often, there are no clinical signs. The condition is frequently an incidental finding during a routine physical exam. - **Grade II:** The classic sign is a sudden, intermittent "skipping" lameness. The dog may take a few steps, then suddenly hold up the hind leg, then put it down and walk normally again. This can be triggered by exercise or even just turning a corner. - **Grade III and IV:** These dogs typically have a persistent lameness. They may have a crouched stance, an abnormal gait, and difficulty jumping or climbing stairs. You may also notice that the knee looks "flat" or that the kneecap is visibly out of place [6]. It is also important to note that patellar luxation is frequently bilateral (affecting both knees), and it is often associated with other orthopedic issues, such as **cranial cruciate ligament (CCL) rupture** [1][7]. In fact, studies show that CCL rupture can be concurrent in up to 40% of MPL cases [1]. This is why a thorough orthopedic examination is vital. ## Veterinary Examination and Diagnostics Diagnosis is primarily based on a physical examination. Your veterinarian will palpate the stifle joint to assess the patella's stability and grade the luxation. This is done by extending and flexing the knee while applying digital pressure to the patella. To confirm the diagnosis and rule out other conditions, radiographs (X-rays) are essential. They allow the surgeon to: - Confirm the direction and severity of the luxation. - Assess the depth of the trochlear groove. - Evaluate the presence and severity of osteoarthritis [8]. - Measure angles like the **tibial plateau angle (TPA)** to plan surgery [9]. - Evaluate for other bone deformities [10]. Advanced imaging, such as CT scans, may be recommended for complex cases, especially those involving femoral deformities, to create 3D models for surgical planning [5]. Recent research has also focused on specific radiographic measurements, like the tibial plateau-patella angle (TPPA), to better characterize patellar position and guide surgical decisions [11]. However, standard measurements of patellar height (like the Insall-Salvati index) have shown poor diagnostic value in differentiating healthy from affected joints, indicating that the pathology is more complex than just a high-riding patella [12][13]. ## Evidence-Based Management: Therapy vs. Surgical Correction The core decision in treating a luxating patella is whether to pursue conservative (medical) therapy or surgical correction. This decision is guided by the grade of the luxation and the clinical signs. ### When is Conservative Therapy Appropriate? Conservative therapy is generally reserved for: - **Grade I luxations:** These are typically asymptomatic and require no treatment. - **Grade II luxations with mild, infrequent lameness:** If the dog only skips occasionally and is not in obvious pain, conservative management may be attempted first. - **Dogs that are poor surgical candidates:** Older dogs or those with other health conditions may not be suitable for anesthesia and surgery. Conservative therapy focuses on managing symptoms and preventing progression. It includes: - **Weight management:** Maintaining a lean body condition is critical to reduce stress on the stifle joint. - **Physical therapy:** Controlled exercises to strengthen the quadriceps and hamstring muscles can help stabilize the patella. - **Anti-inflammatory medications:** Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to manage pain and inflammation during flare-ups. - **Activity modification:** Avoiding high-impact activities like jumping and rough play can reduce the frequency of luxation episodes. It is crucial to understand that conservative therapy does not correct the underlying anatomical deformity. It only manages the symptoms. If a Grade II luxation is causing frequent lameness, or if it progresses to a Grade III, surgery is often the better long-term solution. ### When is Surgery the Best Option? Surgical correction is the treatment of choice for: - **Grade III and IV luxations:** These cause significant, persistent lameness and require realignment to restore function [6]. - **Grade II luxations that are refractory to medical therapy:** If a dog continues to have frequent lameness despite conservative management, surgery is indicated. - **Dogs with concurrent injuries:** If there is a concurrent CCL rupture, surgery is almost always necessary to address both issues [1][7]. The goal of surgery is to realign the quadriceps extensor mechanism and deepen the trochlear groove so the patella can track normally. There are several surgical techniques, and they are often combined for the best outcome [6][2]. ### A Breakdown of Surgical Techniques Surgery for patellar luxation is not a single procedure but a combination of techniques tailored to the individual dog's anatomy. The most common procedures include: 1. **Trochleoplasty (Deepening the Groove):** This procedure deepens the shallow femoral trochlear groove so the patella has a deeper track to sit in. There are several methods: - **Trochlear Wedge Recession (TWR):** A wedge of bone and cartilage is removed, deepened, and replaced. - **Trochlear Block Recession (TBR):** A rectangular block is recessed. - **Kite Shield-Shaped Wedge Recession:** A specific type of wedge recession used in toy breeds, which has shown good results in improving trochlear depth [14]. - **Condroplasty:** In very young dogs, the groove may be deepened by simply pushing the cartilage down, as it is still soft. However, this is less commonly used now. 2. **Tibial Tuberosity Transposition (TTT):** This is one of the most critical components of the surgery. The tibial tuberosity is a bony prominence on the front of the tibia where the patellar ligament attaches. In dogs with MPL, this attachment point is often too far medial (towards the inside). The TTT procedure involves cutting the bone and moving it laterally (towards the outside) to realign the pull of the quadriceps muscle [1][2][7]. 3. **Soft Tissue Releases and Tightening:** The joint capsule on the side the patella is luxating towards is often stretched. This is released (medial release). On the opposite side, the joint capsule is tightened (lateral imbrication) to help hold the patella in place. 4. **Corrective Osteotomies:** In cases with significant femoral or tibial deformities, a corrective osteotomy (cutting and realigning the bone) may be necessary. This is especially true for Grade IV luxations or when there is a "bow-legged" or "knock-kneed" appearance. This can involve a **transverse femoral ostectomy** to correct patella alta [10] or a **cranial closing wedge ostectomy** to address a concurrent CCL rupture [1]. Advanced planning with 3D-printed guides is becoming more common for these complex corrections [5]. 5. **Combined Procedures:** For many dogs, a combination of these techniques is required. For example, a dog with a Grade III MPL may need a trochleoplasty, a TTT, and a joint capsule modification [6]. For dogs with concurrent CCL rupture, a combined procedure like a **TPLO (Tibial Plateau Leveling Osteotomy) and TTT** is a highly effective single-session treatment [7]. ## At a Glance: Therapy vs. Surgical Correction | Feature | Conservative Therapy | Surgical Correction | | :--- | :--- | :--- | | **Best Candidates** | Grade I, mild/intermittent Grade II | Grade II (frequent), Grade III, Grade IV | | **Goal** | Manage pain, slow progression | Correct anatomical deformity, restore normal function | | **Methods** | Weight loss, physio, NSAIDs, activity restriction | Trochleoplasty, TTT, soft tissue repair, osteotomies | | **Recovery Time** | N/A (continuous management) | 6-12 weeks for bone healing, up to 6 months for full return to function | | **Outcome** | May not prevent progression to higher grade | Excellent to good in 80-95% of cases, especially in lower grades [8][6] | | **Risks** | Continued lameness, progression to arthritis | Surgical complications (infection, implant failure, reluxation) [8][6] | ## Post-Surgical Care and Prognosis Post-operative care is as important as the surgery itself. It typically involves: - **Strict rest:** Confinement to a crate or small room for the first 4-6 weeks to allow bone and soft tissue healing. - **Pain management:** A combination of NSAIDs and other pain relievers. - **Physical therapy:** A structured rehabilitation program, starting with passive range of motion exercises and progressing to controlled walks and strengthening exercises. - **Suture removal:** If skin sutures are used, they are removed in 10-14 days. The prognosis after surgical correction is generally very good. Studies have shown that: - In dogs under 10 kg, surgical treatment resulted in a favorable outcome, with owners perceiving an excellent or very good outcome in 95% of dogs [8]. - For Grade 4 MPL, surgery significantly improves limb function, though a return to full function is less guaranteed than in lower grades. In one study, full function was reported in 42.6% of cases, and acceptable function in 40.4% [6]. - The complication rate is relatively low. In one study of small dogs, minor complications occurred in 46% of cases, but major complications requiring revision surgery were only 12.8% [8][6]. - The most common long-term complication is the development of osteoarthritis, which is already present in many cases at the time of surgery [8]. The decision to do unilateral (one knee) or bilateral (both knees at the same time) surgery is a discussion for you and your surgeon. Studies have shown that single-session bilateral surgery has similar complication rates and functional outcomes to unilateral surgery, and it avoids the need for a second anesthetic [15]. ## The Link Between Patellar Luxation and Cranial Cruciate Ligament Rupture It is essential to highlight the strong association between medial patellar luxation and cranial cruciate ligament (CCL) rupture. This is a common and clinically significant comorbidity in small-breed dogs [1]. The biomechanical instability caused by the luxating patella can place abnormal stress on the CCL, leading to its rupture. When both conditions are present, a combined surgical approach is often necessary. Options include: - **TPLO and TTT:** This combination addresses the CCL rupture (TPLO) and the patellar luxation (TTT) in a single procedure. A recent study found this to be a viable option for small-breed dogs, with significant improvement in lameness and MPL grade [7]. - **Modified Cranial Closing Wedge Ostectomy (mCCWO) and TTT:** This is another combined technique that has been shown to be effective in treating both conditions concurrently [1]. If your dog has a patellar luxation, your veterinarian will always carefully assess the CCL to check for concurrent injury. ## Prevention and Long-Term Management While you cannot change your dog's genetics, you can help manage the condition and prevent secondary issues. - **Maintain a Healthy Weight:** This is the single most important thing you can do to reduce stress on the stifle joints. - **Controlled Exercise:** Avoid high-impact activities like jumping on and off furniture. Use ramps or stairs instead. - **Joint Supplements:** While not a cure, supplements containing glucosamine and chondroitin sulfate may help support joint health and slow the progression of osteoarthritis. Discuss this with your veterinarian. - **Regular Veterinary Check-ups:** This allows for early detection of any changes in the grade of the luxation or the development of arthritis. ## Limitations and When to Contact a Veterinarian This article provides a comprehensive overview, but it cannot predict the specific outcome for your dog. The success of treatment depends on a multitude of factors, including the exact grade of luxation, the presence of concurrent orthopedic issues, the surgical technique used, and your dog's individual healing capacity. Breed-level information can only provide a general risk profile; it cannot tell you if your specific dog will develop the condition or how it will respond to treatment. **You should contact your veterinarian immediately if you notice:** - Your dog is suddenly unable to bear weight on a hind leg. - A visible, persistent deformity of the knee. - Severe pain or distress. - Any signs of infection after surgery, such as redness, swelling, or discharge. - Your dog is not using the leg at all within 24 hours after surgery (some limping is expected). Never attempt to "pop" the kneecap back into place yourself, as this can cause further damage to the joint. ## Recognizing the Early Signs: What Owners Notice First The clinical presentation of a luxating patella can be subtle or dramatic, depending on the grade and the individual dog. Owners often describe a characteristic "skipping" gait, where the dog holds a hind leg up for a few steps before returning to normal weight bearing. This is particularly common in Grade II luxations, where the patella pops out of the groove during activity and then spontaneously reduces, often with a quick shake of the leg. The skipping may be more noticeable after exercise, when the dog is turning sharply, or when rising from a resting position. In contrast, dogs with Grade III or IV luxations may exhibit a more persistent lameness. They might carry the affected limb entirely, or they may walk with a crouched, stiff-legged gait. Owners may also observe that the affected knee appears flatter or less defined compared to the opposite limb. In severe cases, the limb may appear rotated or bowed, reflecting the underlying femoral and tibial deformities that often accompany high-grade luxations [6]. It is important to recognize that lameness is not always present. Many dogs with Grade I luxations show no clinical signs at all, and the condition is discovered incidentally during a routine wellness examination. Even some dogs with Grade II luxations may only show signs intermittently, with weeks or months between episodes. This variability can make it tempting to delay veterinary evaluation, but early assessment is valuable. The longer a luxation goes unaddressed, the more opportunity there is for cartilage damage and progressive osteoarthritis to develop [8]. ## The Biomechanical Cascade: Why a Shallow Groove Matters The femoral trochlear groove is the track within which the patella glides during knee flexion and extension. In a normal stifle, this groove is sufficiently deep to cradle the patella and resist medial or lateral displacement. In dogs with patellar luxation, the groove is often shallow, flattened, or even convex in severe cases. This anatomical deficiency is a primary contributor to instability. The depth of the trochlear groove is not the only factor at play. The alignment of the quadriceps muscle group, the position of the tibial tuberosity, and the tension of the joint capsule all contribute to patellar stability. When the quadriceps muscle pull is directed medially, as is common in small breeds with medial luxation, the patella is constantly being pulled toward the inside of the knee. Over time, this abnormal pull can exacerbate the shallowness of the groove and stretch the medial joint capsule, creating a self-perpetuating cycle of instability [4]. Understanding this biomechanical cascade is essential for appreciating why conservative therapy has limitations. While anti-inflammatory medications and physical therapy can address pain and muscle weakness, they cannot change the underlying bone morphology or the direction of the quadriceps pull. Only surgical realignment can correct these structural abnormalities [6]. ## Breed Predisposition and Genetic Considerations Medial patellar luxation is overwhelmingly a condition of small and toy breed dogs. Breeds such as the Chihuahua, Pomeranian, Yorkshire Terrier, Bichon Frise, Maltese, Shih Tzu, and Miniature Poodle are overrepresented. The condition is also seen in larger breeds, but lateral luxation is more common in large and giant breeds, often in association with coxofemoral (hip) abnormalities [2]. The genetic basis of patellar luxation is not fully understood, but it is widely accepted that the condition is heritable. The mode of inheritance is likely polygenic, meaning multiple genes contribute to the risk. This complexity makes it difficult to eliminate the condition through selective breeding alone. However, responsible breeders can reduce the risk by screening breeding stock for patellar luxation and avoiding breeding affected individuals. Orthopedic Foundation for Animals (OFA) screening provides a standardized method for evaluating patellar status in breeding dogs. It is also worth noting that patellar luxation is frequently bilateral. Studies have reported that up to 50% or more of affected dogs have luxation in both stifles, although the grade may differ between limbs [6]. This bilateral nature underscores the importance of a thorough orthopedic examination of both hind limbs, even when clinical signs are unilateral. ## The Diagnostic Workup: Beyond Palpation While palpation is the cornerstone of diagnosis, a comprehensive diagnostic workup involves more than just grading the luxation. Your veterinarian will perform a full orthopedic examination, assessing gait, range of motion, joint stability, and muscle mass. This examination should include evaluation of the hips, stifles, and hocks, as concurrent orthopedic conditions are common. Radiographs are essential for surgical planning. Standard views include a lateral and a craniocaudal (front-to-back) projection of the stifle. These images allow the surgeon to assess the depth of the trochlear groove, the position of the patella, the presence of osteoarthritis, and the alignment of the femur and tibia. In some cases, additional views or stress radiographs may be recommended to evaluate joint stability [8]. For complex cases, particularly those with suspected femoral or tibial deformities, advanced imaging such as computed tomography (CT) may be recommended. CT scans provide three-dimensional information that can be used to create patient-specific surgical guides, improving the precision of corrective osteotomies [5]. This technology is particularly valuable for Grade IV luxations, where the degree of bony deformity is often severe. Recent research has explored additional radiographic measurements to better characterize patellar position. The tibial plateau-patella angle (TPPA) has been proposed as a tool to assess patellar height and guide surgical decision-making [11]. However, other measurements, such as the Insall-Salvati index, have shown poor diagnostic value in differentiating healthy from affected joints, highlighting the complexity of the pathology [12][13]. These findings suggest that patellar luxation is not simply a matter of a high-riding patella, but rather a multifaceted alignment problem. ## Conservative Therapy in Detail: What It Can and Cannot Achieve Conservative therapy is a reasonable first-line approach for Grade I luxations and for Grade II luxations that are causing only mild, infrequent lameness. The goals of conservative management are to reduce pain, improve muscle strength, and slow the progression of osteoarthritis. It is not a cure, and it does not correct the underlying anatomical abnormality. Weight management is arguably the most important component of conservative therapy. Excess body weight places additional stress on the stifle joint, exacerbating pain and accelerating cartilage wear. A lean body condition score is associated with reduced lameness and improved mobility in dogs with osteoarthritis. Your veterinarian can help you determine an appropriate calorie intake and recommend a weight management plan. Physical therapy is another cornerstone of conservative management. Controlled exercises that strengthen the quadriceps and hamstring muscles can help stabilize the patella by improving the dynamic support around the joint. Examples include: - **Sit-to-stand exercises:** These strengthen the quadriceps and gluteal muscles. - **Controlled leash walks:** These maintain joint mobility without excessive impact. - **Underwater treadmill therapy:** This provides low-impact exercise that builds muscle without stressing the joint. - **Passive range of motion exercises:** These maintain joint flexibility and reduce stiffness. Anti-inflammatory medications, typically non-steroidal anti-inflammatory drugs (NSAIDs), are used to manage pain and inflammation during flare-ups. These medications are not intended for long-term daily use in most cases, as they carry potential side effects, particularly with prolonged administration. Your veterinarian will guide you on the appropriate use of these medications. Activity modification is also essential. High-impact activities such as jumping, rough play, and agility training should be avoided or minimized. Instead, encourage low-impact activities like swimming or short, controlled walks on soft surfaces. Using ramps or stairs to help your dog access furniture or vehicles can reduce the risk of luxation episodes. It is important to have realistic expectations about conservative therapy. While it can be effective for managing mild cases, it does not prevent the progression of osteoarthritis. If a dog with a Grade II luxation continues to experience frequent lameness despite conservative management, or if the grade progresses, surgery should be reconsidered. ## Surgical Decision-Making: A Shared Process The decision to pursue surgery is not one to be made lightly. It involves a discussion between you, your primary care veterinarian, and ideally a board-certified veterinary surgeon. Several factors influence this decision: - **Grade of luxation:** Grade III and IV luxations are almost always surgical cases, as they cause significant, persistent lameness and progressive joint damage [6]. - **Frequency and severity of lameness:** A Grade II luxation that causes frequent or severe lameness is a candidate for surgery, even if it is not a high grade. - **Age of the dog:** Surgery can be performed at any age, but it is often recommended earlier in life to prevent the development of secondary osteoarthritis. In young dogs, surgery can also correct deformities before they become more severe. - **Presence of concurrent orthopedic conditions:** If there is a concurrent CCL rupture, surgery is almost always necessary to address both issues [1][7]. - **The dog's overall health:** Dogs with significant systemic disease may not be good candidates for anesthesia and surgery. - **The owner's ability to provide post-operative care:** Successful recovery requires strict rest and a structured rehabilitation program. This commitment must be considered before proceeding with surgery. Your veterinary team will help you weigh these factors and make a recommendation that is in the best interest of your dog. ## Surgical Techniques in Depth Surgical correction of patellar luxation is a highly individualized procedure. The surgeon selects from a range of techniques based on the specific anatomical abnormalities identified during the diagnostic workup. Often, multiple techniques are combined to achieve a stable, well-aligned joint. ### Trochleoplasty: Restoring the Groove Trochleoplasty is the collective term for procedures that deepen the femoral trochlear groove. The goal is to create a track that is deep enough to hold the patella securely during joint motion. Several techniques exist: - **Trochlear wedge recession (TWR):** This technique involves removing a wedge-shaped piece of bone and cartilage from the trochlear groove, deepening the underlying bone, and then replacing the wedge. The cartilage surface is preserved, which is advantageous for long-term joint health. - **Trochlear block recession (TBR):** Similar to TWR, but a rectangular block is removed and recessed. This technique may be preferred in certain cases based on the shape of the groove. - **Kite shield-shaped wedge recession:** This is a modification of the wedge recession technique that has been used successfully in toy breeds. It provides good trochlear depth while preserving the articular cartilage [14]. - **Condroplasty:** In very young dogs, the cartilage is soft enough that the groove can be deepened by simply pressing the cartilage down into the underlying bone. This technique is less commonly used today, as it does not provide as durable a result as wedge or block recession. The choice of trochleoplasty technique depends on the size of the dog, the shape of the groove, and the surgeon's preference. All techniques aim to achieve the same goal: a deeper, more stable track for the patella. ### Tibial Tuberosity Transposition: Realigning the Pull Tibial tuberosity transposition (TTT) is one of the most critical components of surgical correction for medial patellar luxation. The tibial tuberosity is the bony prominence on the front of the tibia where the patellar ligament attaches. In dogs with MPL, this attachment point is often positioned too far medially, causing the quadriceps muscle pull to be directed toward the inside of the knee. The TTT procedure involves cutting the tibial tuberosity with an osteotome or saw, moving it laterally to a more appropriate position, and securing it with pins or screws. This realigns the pull of the quadriceps muscle, reducing the medial force on the patella. TTT is often combined with trochleoplasty and soft tissue procedures for optimal results [1][2][7]. ### Soft Tissue Procedures: Balancing the Joint Capsule The joint capsule and surrounding soft tissues play a significant role in patellar stability. In dogs with MPL, the medial joint capsule is often stretched and lax, while the lateral capsule is relatively tight. Surgical correction typically involves: - **Medial release:** The stretched medial joint capsule is incised or released to reduce the medial pull on the patella. - **Lateral imbrication:** The lateral joint capsule is tightened, or imbricated, to provide a counteracting force that helps hold the patella in the groove. These soft tissue procedures are often performed in conjunction with bony procedures to achieve a balanced, stable joint. ### Corrective Osteotomies: Addressing Bony Deformities In cases of severe luxation, particularly Grade IV, there may be significant deformities of the femur or tibia. These deformities can include femoral varus (bowing of the femur toward the midline), tibial torsion (twisting of the tibia), or patella alta (a high-riding patella). Corrective osteotomies involve cutting the bone and realigning it to restore a more normal limb axis. - **Transverse femoral ostectomy:** This procedure can be used to correct patella alta by shortening the femur [10]. - **Cranial closing wedge ostectomy (CCWO):** This procedure is used to address a concurrent CCL rupture by changing the angle of the tibial plateau [1]. - **Tibial plateau leveling osteotomy (TPLO):** This is another procedure for CCL rupture that can be combined with TTT for dogs with concurrent MPL and CCL rupture [7]. Corrective osteotomies are technically demanding procedures that require careful preoperative planning. Advanced imaging, such as CT, and the use of 3D-printed surgical guides can improve the accuracy of these procedures [5]. ### Combined Procedures for Concurrent CCL Rupture The association between MPL and CCL rupture is well established. The biomechanical instability caused by the luxating patella places abnormal stress on the CCL, increasing the risk of rupture. When both conditions are present, a combined surgical approach is often recommended. - **TPLO and TTT:** This combination addresses the CCL rupture (TPLO) and the patellar luxation (TTT) in a single procedure. A recent study found this to be a viable option for small-breed dogs, with significant improvement in lameness and MPL grade [7]. - **Modified cranial closing wedge ostectomy (mCCWO) and TTT:** This is another combined technique that has been shown to be effective in treating both conditions concurrently [1]. The choice of combined procedure depends on the specific anatomy of the dog and the surgeon's preference. Both approaches have shown good outcomes in clinical studies. ## Post-Surgical Recovery: A Detailed Roadmap Post-operative care is critical to the success of patellar luxation surgery. The recovery period can be divided into several phases, each with specific goals and restrictions. ### Phase 1: Immediate Post-Operative Period (Days 0-14) The first two weeks after surgery are focused on pain management, wound care, and protecting the surgical site. Your dog will likely be discharged with a combination of medications, including NSAIDs, opioid pain relievers, and possibly antibiotics. - **Rest:** Strict rest is essential. Your dog should be confined to a crate or a small room with limited space. This prevents excessive movement that could disrupt the surgical repair. - **Leash walks:** Short, leash-controlled walks are permitted only for elimination purposes. These walks should be kept very brief, just long enough for your dog to urinate and defecate. - **Incision care:** Monitor the incision daily for signs of infection, such as redness, swelling, discharge, or excessive licking. An Elizabethan collar (cone) may be necessary to prevent your dog from licking the incision. - **Cold therapy:** Applying a cold pack to the surgical site for 10-15 minutes several times a day can help reduce swelling and pain. ### Phase 2: Early Rehabilitation (Weeks 2-6) As your dog begins to heal, a structured rehabilitation program can be introduced. This phase focuses on restoring range of motion and beginning gentle strengthening exercises. - **Passive range of motion (PROM) exercises:** Your veterinarian or a rehabilitation therapist can teach you how to perform PROM exercises on your dog's stifle. These exercises help maintain joint flexibility and prevent stiffness. - **Controlled walking:** The duration of leash walks can be gradually increased, but should remain short and controlled. Avoid running, jumping, and stairs. - **Physical therapy:** Depending on availability, your dog may benefit from professional physical therapy, including underwater treadmill therapy, therapeutic ultrasound, and laser therapy. ### Phase 3: Strengthening and Return to Function (Weeks 6-12+) By this phase, bone healing is typically well advanced, and your dog can begin more active strengthening exercises. - **Sit-to-stand exercises:** These can be introduced to strengthen the quadriceps and gluteal muscles. - **Controlled stair climbing:** If your dog is comfortable, short sessions of stair climbing can be introduced. - **Gradual return to normal activity:** Over the course of several weeks, your dog can gradually return to normal activity levels. However, high-impact activities such as jumping and rough play should still be limited. The full recovery period can take up to six months or longer, depending on the complexity of the surgery and the individual dog. Regular follow-up appointments with your veterinarian are essential to monitor healing and adjust the rehabilitation plan as needed. ## Prognosis and Long-Term Outcomes The prognosis after surgical correction of patellar luxation is generally favorable. Studies have reported good to excellent outcomes in the majority of cases, particularly for lower-grade luxations. - In dogs under 10 kg, surgical treatment resulted in a favorable outcome, with owners perceiving an excellent or very good outcome in 95% of dogs [8]. - For Grade 4 MPL, surgery significantly improves limb function, though a return to full function is less guaranteed than in lower grades. In one study, full function was reported in 42.6% of cases, and acceptable function in 40.4% [6]. - The complication rate is relatively low. In one study of small dogs, minor complications occurred in 46% of cases, but major complications requiring revision surgery were only 12.8% [8][6]. The most common long-term complication is the progression of osteoarthritis. Many dogs already have some degree of arthritis at the time of surgery, and the condition may continue to progress despite successful realignment [8]. This is why long-term management, including weight control and joint supplements, is important even after successful surgery. ## Special Considerations for Toy and Small Breeds Toy and small breeds present unique challenges in the surgical management of patellar luxation. Their small size means that implants and surgical instruments must be appropriately sized. The bone is also more fragile, requiring careful handling to avoid fractures. The kite shield-shaped wedge recession technique was specifically developed for use in toy breeds, as it provides good trochlear depth while preserving the articular cartilage [14]. This technique has shown good results in improving trochlear depth and stabilizing the patella. Another consideration is the potential for concurrent orthopedic conditions. Small breeds are also prone to Legg-Calvé-Perthes disease (avascular necrosis of the femoral head) and medial shoulder instability, among other conditions. A thorough orthopedic examination is essential to identify all sources of lameness. ## The Role of Owner Observation in Early Detection As an owner, you are the first line of defense in detecting patellar luxation. Being observant of your dog's gait and behavior can lead to earlier diagnosis and treatment, which can improve outcomes. Pay attention to: - **Skipping or hopping:** A sudden, intermittent "skipping" gait is a classic sign of a Grade II luxation. - **Holding up a hind leg:** If your dog frequently holds up a hind leg, especially after exercise, this may indicate a luxation. - **Difficulty rising or jumping:** Dogs with higher-grade luxations may have difficulty rising from a lying position or jumping onto furniture. - **Abnormal stance:** A bow-legged or knock-kneed stance can indicate a severe luxation. - **Licking or chewing at the knee:** Some dogs may lick or chew at the affected knee due to discomfort. If you notice any of these signs, it is important to schedule a veterinary examination. Early diagnosis allows for earlier intervention, which may slow the progression of osteoarthritis and improve the long-term prognosis. ## Preparing for the Veterinary Visit A veterinary visit for a suspected luxating patella can be more productive if you come prepared. Here are some steps you can take: - **Record a video:** If your dog shows intermittent lameness, try to capture a video of the behavior. This can be invaluable to your veterinarian, as the lameness may not be apparent during the examination. - **Note the frequency and duration of lameness:** Keep a log of when the lameness occurs, how long it lasts, and what seems to trigger it. - **Bring a list of questions:** Write down any questions you have about the condition, treatment options, and prognosis. - **Be prepared to discuss your dog's history:** This includes information about when you first noticed the lameness, any previous injuries, and your dog's activity level. During the examination, your veterinarian will palpate the stifle joint to assess patellar stability and grade the luxation. They may also recommend radiographs to confirm the diagnosis and plan for treatment. ## Prevention Strategies: What Owners Can Do While you cannot change your dog's genetics, you can take steps to reduce the risk of complications and slow the progression of the condition. - **Maintain a healthy weight:** Excess weight places additional stress on the stifle joint, exacerbating pain and accelerating cartilage wear. - **Provide a balanced diet:** A diet that supports joint health, including appropriate levels of omega-3 fatty acids, may be beneficial. - **Avoid high-impact activities:** Jumping on and off furniture, rough play, and agility training can increase the risk of luxation episodes. - **Use ramps or stairs:** Help your dog access furniture or vehicles by using ramps or stairs instead of allowing them to jump. - **Consider joint supplements:** Supplements containing glucosamine and chondroitin sulfate may help support joint health and slow the progression of osteoarthritis. Discuss this with your veterinarian. - **Regular veterinary check-ups:** This allows for early detection of any changes in the grade of the luxation or the development of arthritis. ## When to Seek Immediate Veterinary Care While patellar luxation is rarely an emergency, there are situations where immediate veterinary care is warranted. - **Sudden inability to bear weight:** If your dog is suddenly unable to bear weight on a hind leg, this could indicate a more serious injury, such as a CCL rupture or a fracture. - **Visible deformity:** A visible, persistent deformity of the knee may indicate a severe luxation or a fracture. - **Severe pain:** If your dog is in severe pain, is crying, or is reluctant to move, seek veterinary care immediately. - **Post-surgical complications:** If your dog is not using the leg at all within 24 hours after surgery, or if there are signs of infection such as redness, swelling, or discharge, contact your veterinarian immediately. Never attempt to "pop" the kneecap back into place yourself, as this can cause further damage to the joint. ## The Importance of a Team Approach Managing a luxating patella is a team effort. It involves you, your primary care veterinarian, and potentially a board-certified veterinary surgeon and a rehabilitation therapist. Each member of the team plays a vital role in ensuring the best possible outcome for your dog. - **You** are responsible for observing your dog, providing daily care, and following the treatment plan. - **Your primary care veterinarian** is responsible for diagnosing the condition, recommending treatment, and providing ongoing care. - **The veterinary surgeon** is responsible for performing the surgery and managing any complications. - **The rehabilitation therapist** is responsible for guiding the recovery process and helping your dog regain strength and mobility. By working together, this team can help your dog achieve the best possible quality of life. ## Long-Term Monitoring and Quality of Life Even after successful treatment, long-term monitoring is important. Dogs with patellar luxation are at increased risk for developing osteoarthritis, and this condition may require ongoing management. Regular veterinary check-ups, at least annually, are recommended. These check-ups should include a full orthopedic examination to assess joint health and detect any changes in the grade of the luxation. Radiographs may be repeated periodically to monitor the progression of osteoarthritis. Quality of life is an important consideration. Most dogs with patellar luxation, even those with high-grade luxations, can enjoy a good quality of life with appropriate treatment. They may not be able to compete in high-level agility or participate in strenuous activities, but they can be happy, comfortable companions. If you have any concerns about your dog's quality of life, discuss them with your veterinarian. There are many options available to manage pain and improve mobility, and your veterinary team can help you find the right approach for your dog. -- ## Related Clinical & Scientific Guides * [Immune-Mediated Polyarthritis IMPA: Joint Pain, Fever and Steroid Protocol](/knowledge/veterinary-medicine/orthopedic-mobility/immune-mediated-polyarthritis-impa-joint-pain-fever-and-steroid-protocol) * [Hip Dysplasia in Dogs: Hip Replacement vs FHO vs Conservative Management](/knowledge/veterinary-medicine/orthopedic-mobility/hip-dysplasia-in-dogs-hip-replacement-vs-fho-vs-conservative-management) * [Thermoregulating & Heated Dog Beds: Infrared Heat Safety, Temperature Calibration, and Arthritis Relief](/knowledge/veterinary-medicine/orthopedic-mobility/heated-dog-bed-senior-arthritis)