Patella (kneecap) luxation is a common orthopedic problem affecting both our small and large canine friends.This condition typically results from abnormalities in bony development of the hind limbs. The patella is a small bone that is part of the extensor (quadriceps) mechanism. It sits just inside the trochlear groove at the end of the femur (thigh bone). It helps to direct the pull of the quadriceps muscles in the way that a pulley redirects a cable.The patella is found within the patellar ligament, which attaches to the point of the tibia (shin bone).This mechanism allows for pain-free and efficient extension of the stifle (knee). If the patella is luxated either to the inside or outside of the stifle, then this efficiency is severely affected, causing pain and stress around the stifle. Furthermore, if the patella is able to pop in and out, then wear and tear on the cartilage of both the patella and trochlear ridge occurs, resulting in osteoarthritis.
無論在大型犬還是小型犬，髕骨（膝蓋骨）脫位是一種常見的骨科疾病。通常是由於後肢的骨發育不良引起的。髕骨是一塊附屬於股四頭肌的小骨頭。他位於股骨末端的滑車溝當中。它能協助引導股四頭肌的拉力，就像滑輪引導繩索一樣。與髕骨相連的是髕韌帶，髕韌帶另一端附著於脛骨。這種結構使得膝關節在伸展的時候不會感到疼痛，並且能很好地伸展。無論髕骨是向內側脫位還是向外側脫位，膝關節伸展的功能將受到嚴重的影響，導致膝關節的疼痛和壓迫。如果髕骨能夠滑出和歸位，那麼將會出現軟骨的磨損以及滑車脊的出現，導致骨關節炎。
How does this occur?
髕骨脫位是如何出現的？
Patella luxations occur from a developmental disorder that occurs after birth.The exact causes are still unknown; however, it is thought that changes beginning at the hip are partially responsible.The changes at the hip result in a sequence of skeletal changes of the thigh and shin bones.The changes noted are outward bowing of the thigh bone causing an inward angle as well as internal rotation of the end of the thigh bone. Furthermore, the top shin bone will develop with an inward angle with internal rotation so that the point of the shin will be facing towards the inside of the leg. Because of these changes the extensor mechanism has a tendency to pull the patella to the inside of the knee.These changes are noted with the most common type of patella luxation, known as a medial patella luxation (MPL). If a lateral patella luxation occurs (LPL), the changes noted are opposite of an MPL Lastly, the trochlear groove where the patella should be located is often times under-developed, leaving it shallow.
髕骨脫位起源於出生後的骨骼發育不良。確切原因仍不清楚，但有些人認為髖關節的變化可以作為部分解釋。髖關節的變化會引起股骨和脛骨的一系列變化。這種變化是股骨的向外彎曲，導致股骨末端會有一個向內側的角度同時股骨末端會向內旋。除此之外，脛骨結節也會有一個向內側的角度同時內旋，這樣脛骨結節就會朝向大腿的內側。這些變化會導致膝關節在伸展的時候，會推動髕骨向內側移動。這種變化是比較常見的髕骨脫位類型，稱為髕骨內側脫位（MPL）。如果是髕骨外側脫位（LPL），則以上的變化則是相反的。最後，髕骨所在的滑車溝往往發育不良，滑車溝變淺。
Clinical Signs and Diagnosis
臨床症狀及診斷
Oftentimes an intermittent lameness will be noted beginning at a young age. It is common to note that dogs will have a bunny-hopping gait or will tend to skip. If the patella is popping in and out, dogs will sometimes kick their leg out almost as if stretching it while walking or running.This occurs when the patella luxates and the dog is trying to get it back into a normal place. Sometimes a cry or yelp may be heard when the patella luxates, and the dog may hold the leg up and not use it.With long-standing patella luxations, muscle loss may be noted in one or both hind limbs.
在犬年輕的時候通常會注意到出現間歇性的跛行。一般也會注意到犬會出現兔子跳步態或者經常走走跳跳。如果髕骨經常滑進滑出，犬會偶爾向前踢腿，就好像在行走或者跑步時伸展後肢一樣。這是因為當髕骨脫位時，犬嘗試著把它回復到正常位置引起的動作。有時候髕骨脫位時犬會發出尖叫，然後把腿抬起來，不願意去使用它。如果是長期的髕骨脫位，單側後肢或者雙側後肢可能會出現肌肉萎縮。
An orthopedic examination is needed to diagnose the problem. On exam the patellas are located, if they are found within the correct location they are attempted to be luxated; on the other hand if the patellas are found either inside or outside the knee then they are attempted to be put back into place. After the examination the grade of luxation is determined on a scale of I-4. A grade I patella luxation is classified as the patella being in the correct location; it can be luxated but pops back into place.This differs from a grade 2 patella luxation wherein the patella is in the correct location, but once luxated will not easily pop back in.With grade 3 and 4 luxations, the patella is always in a luxated position, while with a grade 3 the patella can be reduced versus a grade 4 the patella can not be reduced. Radiographs (X-rays) are taken to determine the location of the patella, if there is any underlying arthritis, as well as any bony abnormalities.
需要進行骨科檢查來診斷這種疾病。檢查時先確認髕骨的位置，如果他們在正確的位置上，嘗試將他們往內側或外側推，使他們被動脫位；如果他們是內側脫位或者外側脫位，則嘗試將他們推回正確的位置。這些檢查將髕骨脫位分為四級。一級指的是髕骨在檢查時處於正確位置，被動脫位後能夠彈回正確的位置。二級與一級的區別在於，兩者在檢查時都處於正確的位置，但是二級脫位時髕骨被動脫位後不那麼容易彈回正確的位置。三級脫位與四級脫位的區別在於，兩者在檢查時髕骨都處於脫位狀態，但是三級脫位髕骨可以被推回正確的位置[，而四級脫位時髕骨無法被推回正確的位置。
How is this treated?
如何進行治療？
For mild luxations (grade I and non-clinical grade 2), surgery is typically not indicated; however, formal rehabilitation to strengthen the quadriceps muscle and improve patellar tracking is beneficial. Furthermore, formal rehabilitation may help in preventing worsening of the clinical signs, and may result in avoidance of surgery in select cases.
對於輕度的髕骨脫位（一級脫位和沒有臨床症狀的二級脫位），不推薦進行手術，但是可以通過適當的復建來提升股四頭肌的力量和改善髕骨軌跡。除此之外，適當的復健可以防止臨床症狀進一步惡化，避免到達需要手術的階段。
Surgery is indicated in cases of grade 3 and 4 luxations as well as with grade 2 luxations that are causing clinical signs. For surgery, your dog would be placed under general anesthesia; a small incision is made on either the inside or outside of the stifle. Once the stifle joint is exposed, the trochlear groove will be evaluated. If it appears shallow, then a deepening of the groove will take place (trochleoplas1y).This is completed by removing a small block of cartilage, deepening the underlying bone and replacing the cartilage back. Additionally, the soft tissues on the side towards the luxation will be released while the soft tissues opposite the side of luxation will be tightened (imbricated). In some cases, a small cut is made in the point of the shin bone and the bone is moved towards (tibial tuberosity transposition) the side opposite the luxation to improve the overall alignment.This small cut in the bone is then held in place by small wires
當髕骨脫位達到三級和四級，或者有臨床症狀的二級脫位時，則建議進行手術。進行此項手術需要進行常規麻醉，然後在膝關節的內側或外側做一個小切口。暴露膝關節後，會對滑車溝進行評估。如果滑車溝較淺，那麼會進行滑車溝加深手術。即先移除一小塊滑車溝軟骨，然後加深下面的骨頭，再將軟骨放回去，手術也就完成了。除此之外，在髕骨脫位方向的軟組織會被鬆弛，同時脫位的對側方向的軟組織會被收緊。一些病例會在脛骨結節做一個小的切口，然後將骨頭移向與髕骨脫位方向相對的一側（脛骨結節移位術，TTT），從而改善整體的角度。最後用鋼絲將骨頭上的切口固定。
What happens after surgery?
術後會發生什麼？
AtVOSM, immediately after surgery radiographs are taken to ensure the patella is located back into its correct location and that the wires are in the correct area.Your dog is then taken to our recovery ward where they are maintained on IV pain medications and under constant care 24 hours a day. Most patients go home the day after surgery.
在VOSM，在術後會立即拍X光片，確認髕骨被歸位到正確的位置，以及鋼絲也在正確的位置。接著動物會移入康復病房，在那會接受靜脈注射的止痛藥物以及一天的24h照護。大部分的病患在術後一天就回家了。
To allow for adequate healing time, it is very important that there be no running, jumping, or playing fora period of 8-12 weeks.Ithis will allow time for the bone to heal if it was cut as well as the soft tissues to heal. During the recovery process beginning approximately 2 weeks after surgery, we recommend patients begin physical rehabilitation to speed up healing, improve range of motion, and build up muscle mass.
建議在術後的8-12周內儘量不要進行奔跑、跳躍或者過度玩耍，以便有足夠的恢復時間。這樣能夠讓受到切割的骨頭以及軟組織進行恢復。在術後2周後，我們會推薦動物開始進行物理復健來提高恢復的速度，增加肢體的活動範圍，增加肌肉量。
Following surgery atVOSM,we recommend that patients begin oral joint supplements (Dasuquin Advanced, Nutramax Labs), omega-3 fatty acids (Welactin, Nutramax Labs), maintain a healthy body weight, and remain active once healed from surgery. These things will be the building blocks along with surgery to minimize and slow down the progression of osteoarthritis.
我們會推薦動物在術後開始服用關節藥物（Dasuquin），Ω-3脂肪酸（Welactin），同時維持健康的體重，痊癒之後可以恢復活動。這些東西將與手術一起成為減少和減緩骨關節炎進展的基石。
Are there any possible comp/ications?
有沒有什麼併發症？
As with any surgery, there is always the possibility for complications. AtVOSM we take all precautions necessary to minimize any complications. Unfortunately, the most common complication after patella luxation repair is luxation of the patella; however, in most cases if this occurs it is typically to a lesser grade, and infrequently needs additional surgery. If the patella luxates after surgery and begins to cause a clinical problem then additional surgery may be recommended.
任何手術都有可能有併發症。VOSM會採取所有必要的預防措施來防止出現併發症。不幸的是，髕骨脫位術後最常見的併發症就是復發髕骨脫位。然而在大部分的病例，如果出現這種情況，復發的脫位不會特別嚴重，不經常需要額外的手術。但是如果術後復發脫位，並且開始引起臨床問題，那麼我們會推薦進行額外的手術。
Other complications to consider are infection after surgery; however; infection rates are very low after this type of surgery. Furthermore, to ensure keeping infection rates low you dog will receive antibiotics before, during, and after surgery. Additionally, just as if any individual human or animal undergoes anesthesia, it is considered very safe, but there are risks involved. Because of these risks, a complete physical exam and blood work is completed by one ofVOSM’s specialists. During surgery your pet will be monitored by one our trained staff members at all times to ensure the highest level of monitoring and safety.
其他的併發症可能是感染，但是這種手術的術後感染速率會非常低。除此之外，為了降低感染速率，動物在術前術中術後都需要使用抗生素。另外，無論是人還是動物，在進行麻醉時，都會存在麻醉風險。因此在術前會進行完整的理學檢查和血液檢查。在術中我們會安排受過訓練的獸醫全程進行監護，保證麻醉的高級監護和安全。