Tibial Tubercle Osteotomy

Transcription

1 Techniques in Knee Surgery 2(1):28 42, 2003 T E C H N I Q U E 2003 Lippincott Williams & Wilkins, Inc., Philadelphia Tibial Tubercle Osteotomy JACK FARR, M.D. Clinical Associate Professor of Orthopaedic Surgery, Indiana University School of Medicine Indianapolis, Indiana, U.S.A. ABSTRACT The patellofemoral joint presents a complex challenge to the surgeon. There are many surgical options for treatment, but none is universally successful in all cases. Tibial tubercle osteotomy has a long history in the distal approach to treating patellar problems. The current approach to the patellofemoral joint continues to evolve. Previous standard measurements and treatments are being re-examined, and with this, the role of moving the tubercle in the treatment of patellar pain and/or instability. Present techniques attempt to optimize joint stability and contact area without increasing articular cartilage stress. Keywords: anteromedialization, patella, patellar dislocation, patellofemoral pain, tubercle osteotomy HISTORICAL PERSPECTIVE Tibial tubercle osteotomy represents one technique for addressing problems with patellofemoral pain and dysfunction. The multifaceted problems of the patellofemoral joint cannot be universally treated by any one surgery, and this equally applies to tibial tubercle surgery. The premise of tubercle surgery is that some patients with patellofemoral problems have, as a basis of these problems, an abnormal (or suboptimal) position of the tubercle. The surgeries may be categorized on how they affect the tubercle in the coronal plane (medial, lateral, proximal, distal) and the sagittal plane (anteriorization). History has demonstrated that the patellofemoral joint is highly sensitive over time to changes in stress. The Hauser procedure called attention to this concern when degeneration was observed in the long term 1,2 (Fig. 1). Tubercle osteotomy requires a comprehensive evaluation of the entire lower extremity, as many of the imbalances of the patellofemoral joint cannot be assigned solely to Address correspondence and reprint requests to Jack Farr, M.D., OrthoIndy, 5255 East Stop 11 Road, Suite 300, Indianapolis, IN, indyknee@hotmail.com Dr. Farr is a Mitek consultant, designed the Tracker AMZ guide, and receives royalties. FIG. 1. Medial patellofemoral arthrosis after Hauser. the position of the tubercle. Two observations are useful when contemplating tubercle surgery: (1) abnormal constraint and increased stress lead to articular cartilage overload with the potential of degeneration, and (2) no single procedure can be applied as a cure-all for patellofemoral problems. The assumption that the original tubercle position is abnormal or suboptimal for distributing force is the reason for moving the tubercle to a new position. Patellofemoral scholars continue to debate the current relevance of tubercle surgery, but review of past clinical outcomes would suggest that with proper indications, tubercle surgery still plays a role in the patellofemoral surgical armamentarium. 3,4 By far the most commonly performed tubercle surgery is medialization, popularized in the United States as the Elmslie-Trillat procedure. 5,6 Reviewing the underlying principles of this surgery may serve as a guide in evaluating the other, less commonly performed tubercle surgeries. In this case, the main premise is that the source of patellofemoral dysfunction (instability or pain) is a result of an abnormal, lateral position of the tubercle. Correcting an abnormal tubercle position suggests that there exists a known normal. Normal infers a median value with standard deviations. With this approach, with a 95% confidence level, 5% of the population by defi- 28 Techniques in Knee Surgery

2 Tibial Tubercle Osteotomy nition would be abnormal. This is not the typical use of these terms in categorizing patellofemoral patients. Instead, the common values often used as normal or abnormal are more related to the values measured in patients with or without patellofemoral problems. When comparing tubercle position to other anatomic landmarks, it is easy to focus at the knee. However, it must be appreciated that tubercle position relative to these other landmarks may be affected by femoral and tibial rotation, and in those cases, addressing the primary site of the abnormality may be more appropriate. The two common clinical measurements of tubercle relative position are the Q angle and the tubercle sulcus angle. The Q angle is measured from the iliac crest to the center of the reduced patella to the center of the tubercle measured either in extension or low levels of flexion. The tubercle sulcus angle is measured at 90 of flexion. This angle is formed by two lines. One line runs from the center of the sulcus distally and is perpendicular to the epicondylar line. The other line runs from the center of the patella to the center of the tibial tubercle. Although normal values are readily available in the literature, it must be noted that ranges are quite large, and there is poor reproducibility of repeated measurements. 7,8 While there may be comfort in using these numbers, their value in determining pathology remains in debate. Post 9 reviewed the literature on the examination of the patellofemoral joint. He found such a high variability in what is considered normal that at present, there is no universally accepted normal or abnormal. This highlights the difficulty of assigning problems of the patellofemoral joint to the position of the tubercle. Thus, at present, the decision to move the tubercle remains somewhat intuitive based on the background of the surgeon, a critical review of the literature, and a broad appreciation of the entire lower extremity. On the other hand, the literature has many reports of positive outcomes with medialization and Fulkerson anteromedialization of the tubercle Therefore, until science catches up with current practice, the surgeon must very carefully evaluate the decision to move the tubercle (and the rationale of the distance and direction of the move). In light of these limitations, an appreciation of the controversy surrounding normals and abnormals remains useful. With the known ill effects of increasing stress, a secondary goal of any tubercle surgery change of patellar tendon force vector is to improve or maintain contact area without increasing force on the joint. Surgery in the sagittal plane is only anterior, as posteriorization has been shown to increase force at the patellofemoral joint leading to degeneration. 2 The concept of anteriorization was popularized by Maquet 15 as a treatment for degeneration of the patellofemoral joint. This was based largely on two-dimensional static biomechanical analysis. Although the theoretical resultant force vector may be reduced, in reality, the calculation is quite complex and will require three-dimensional realtime analysis of both force and contact area as they vary through loaded range of motion. As the anteriorization also rotates the patella in the sagittal plane (rotation of the superior pole of the patella toward the femur) not only the forces but also the contact area change at different ranges of motion. In the normal knee, the force and contact area are uniquely matched so that at high loads, there are also larger contact areas; thus, with flexion, the increased stress is less extreme than without this safeguard. 16 Even if surgery decreases the force in the abnormal knee, if the rotation causes the contact area to diminish, the stress may actually increase (stress force per unit area). Fulkerson 12 combined the theoretical advantages of both the Maquet anteriorization procedure (to decrease patellofemoral forces) and medialization (to improve joint congruity); thus, this procedure is termed anteromedialization (AMZ) (Fig. 2). The AMZ achieved this by an oblique cut between the sagittal and coronal planes. The obliquity can be altered to achieve the same degree of elevation (typically 1.5 cm) with various degrees of medialization (the steeper the cut, the less medialization). In fact, with an offset of local bone graft, the result can be anteriorization without medialization. 17 In addition to addressing two concerns (chondrosis and subluxation), the procedure had fewer complications than the Maquet and did not require iliac bone graft harvest. 18 Using similar logic, with reversal of the oblique cut, it is possible to perform an anterolateralization, which Fulkerson 19 has shown to improve symptoms in patients with iatrogenic medial pain and degeneration such as that which occurs after a Hauser procedure. Proximalization of the tubercle is directed at treating patellar baja (infera), which in most cases occurs after an arthrofibrotic response to trauma typically surgery. 20 This is an alternative to patellar tendon lengthening and may be performed with several variations. On the other hand, distalization is typically for treatment of congenital patella alta associated with patellar instability. As such, it is usually a component of other treatments to address patellar stability and not an isolated procedure, as many patients with patellar alta have a low recurrence rate of dislocation. 21 INDICATIONS/CONTRAINDICATIONS Indications for tibial tubercle surgery may be categorized into seven overlapping groups as outlined in Table 1. Obviously, the total number of patellofemoral diagnoses is much larger, as are the multiple treatment options. In light of the variability of the human perception of pain and the many subsets of pathoanatomy, a thorough physical therapy program precedes any surgical indication. During this period, the surgeon will get to know the Volume 2, Issue 1 29

3 J. Farr FIG. 2. Comparing Maquet, Elmslie- Triatt, and AMZ. patient s postoperative rehabilitation potential and level of pain tolerance, and will be better able to localize the pain so that procedures specific for the patient s pathoanatomy may be applied. In addition, the response to different therapy methods may aid in the decisionmaking process (e.g., the response to a patellar tracking brace). Once again, these options are only in regard to the tibial tubercle after it has been systematically determined that tubercle surgery is necessary in the treatment of a patient s patellofemoral problem. A thorough review of all patellofemoral options should precede planning any of these tubercle surgeries. The total patellofemoral problem is usually complex. It is quite likely that tubercle surgery will not be done in isolation, but rather will often be combined with lateral release and/or repair/reconstruction of the medial patellofemoral ligament. Thorough knowledge of the role of the medial patellofemoral ligament in patella instability should be reviewed before the final decision is made to move the tubercle. 4 Note that the term malalignment has not been applied, as there remains much confusion over the term and its implications, as discussed by Grelsamer. 22 A new category of indications is emerging and evolving. These indications are for tubercle surgery when used in conjunction with articular cartilage restoration (Table 2). Without going into the controversy of cartilage restoration options, the underlying goal when treating any compartment of the knee with cartilage restoration is to unload the treated compartment. This is the basis for correcting subluxation of the patella to improve contact area, and often this is combined with the additional unloading offered by Fulkerson AMZ, as discussed by Peterson et al. 23 and Minas. 24 Highly controversial is the role of anteriorization when cartilage restoration is performed for isolated trochlear lesions. On the surface of the debate, it is intuitive that if anteriorization would be used to unload an isolated patellar chondral lesion, the other half of the joint (trochlea) would be treated in a similar manner. Intuition, however, must be evaluated in the laboratory. These questions may also be considered when transplanting the patellofemoral joint. When bipolar lesions are treated with osteochondral shells, Bugbee and Conver 25 typically do not move the tubercle, while others may combine the allograft transplantation with AMZ (Fig. 3A, B]. Clinical work is awaiting scientific validation; thus, caution should be exercised in these situations. Finally, proximal and distal displacements of the tibial tubercle are for opposite ends of the spectrum (Table 3). Distalization of the tubercle is used typically in patients with increased patellar mobility and delayed entrance into the constraints of the trochlea. This procedure is usually performed in conjunction with concomitant treatment such as repair/reconstruction of the medial patellofemoral ligament or some degree of medialization of the tubercle. On the other hand, proximalization is usually a component of extensive salvage surgery for the patella infera associated with advanced arthrofibrosis. In this case, reviewing the arthrofibrosis literature demonstrates proximalization is only one small part of an approach to modifying a complex and serious problem Techniques in Knee Surgery

4 Tibial Tubercle Osteotomy TABLE 1. Tibial tubercle surgery for specific patellofemoral problem noting these are often combined with various proximal procedures 1. Chronic Patellar Subluxation Medialization Option With recurrent instability (see Arendt (4)) regarding medial patellofemoral ligament) No pain (between instability) Increased T-S angle Chondrosis O-II 2. Chronic Patellar Subluxation Medialization No instability Pain Increased T-S angle Chondrosis O-II 3. Chronic Patellar Subluxation Anteromedialization With or without instability (Evaluated medial patellofemoral ligament) Pain Increased T-S angle Chondrosis III-IV 4. Normal Patellar Position Medialization No instability Pain Increased T-S angle Chondrosis O-II 5. Normal Patellar Position [LH1] Anteromedialization No instability Pain Increased T-S angle Chondrosis III-IV 6. Normal Patellar Position No instability Steep Antermedialization Pain Anteriorization Increased T-S angle Chondrosis III-IV 7. Medial Patella Post-Hauser Anterolateralization No instability Pain Chondrosis Decreased T-S angle The most common contraindication is pain or instability that does not have a rational biomechanical or articular cartilage basis. All rational conservative measures must have failed, or there is documentation of why they would fail. Altering the force and force vector will have no positive result if the pathology cannot be attributed to specific abnormalities. Certainly global anterior knee pain is a contraindication, as is generalized dehabilitation patellofemoral pain. A specific pathoanatomic contraindication common to these techniques occurs if the site of the pathology will have an increased load as a result of TABLE 2. Tibial tubercle surgeries for use in conjunction with cartilage restoration 1. Patellar and/or Trochlear Anteromedialization Cartilage Restoration when chronic subluxation is present 2. Isolated trochlear Cartilage Possible Anteriorization Restoration with normal alignment the realignment. A case in point is superior pole or superior medial chondrosis when considering an AMZ. This injury is common with dashboard posttraumatic chondrosis. Likewise, extensive trochlear involvement decreases the positive outcomes with AMZ; thus, in advanced chondrosis situations, preoperative planning should include contemplation of cartilage restoration options. With end-stage bone on bone arthrosis, rather than attempting an isolated anteriorization or AMZ, arthroplasty may be considered using standard metal and plastic arthroplasty or biologic arthroplasty (osteochondral shell allograft). As one underlying premise to the success of some these procedures is a decrease in stress, it should be expected that some body weights are so high that the postoperative stress levels (even with reduction) will still overload the joint and cause symptoms. As previously discussed, abnormal alignment may actually be distant from the knee, such as excessive anteversion of the femur/hip. In that case, the abnormality should be addressed at the source. The remaining (relative) contrain- Volume 2, Issue 1 31

5 J. Farr FIG. 3. (A) Preoperative subluxation and joint space narrowing. (B) After combined patellofemoral bipolar allograft transplantation and AMZ. dications are those shared with other realignment surgery. These would include a systemic or local inflammatory disease or involvement of the other compartments of the knee. PREOPERATIVE PLANNING As is evident in the discussion of indications, the first phase of preoperative planning is a patient-specific rehabilitation program. Optimally rehabilitated extremities will recover from the insult of surgery faster than patients with an atrophic extremity. This will also aid in a more focused diagnosis, which in turn aids in a more rational approach to surgical technique selection. As with any surgery, the history and physical lay the groundwork. In this case, the focus is on whether or not there are patellar subluxation/dislocations as opposed to the common report of giving way. The next goal is to note inciting activities of both instability and pain. On exam, pain must be as well localized as possible by the surgeon. Once the decision is made that the problem is instability, pain, or both, the underlying pathoanatomy is investigated. Patellar subluxation/dislocation patients have increased lateral displacement, and it is often associated with apprehension. With the limitations of the physical examination explained by Post, 26 it remains a goal to identify certain ranges of the patient s anatomy, such as excessive lateral position of the tubercle or J sign so excessive as to be expressed as subluxation during knee extension. These physical findings will allow tempered interpretation of additional studies. While the literature outlines many advanced techniques such as CT, dynamic MRI, and Gadolinium postexercise cartilage enhancement MRI, most decisions can be made combining an axial view such as the Merchant view (Fig. 4) with weight-bearing AP and lateral views (Fig. 5A, B) supplemented with direct arthroscopic inspection of the articular surfaces. 27 These studies are not only important to determine the appropriate patellofemoral surgery but also useful to evaluate the medial and lateral compartments in which pathology may contraindicate isolated patellofemoral surgery. Once it has been determined that TABLE 3. Proximal and distal displacement surgery of the tibial tubercle 1. Patellar instability with patellar alta as one component 2. Patella infra (baja) as a component of arthrofibrosis Distalization in conjunction with a more primary patellofemoral surgery Proximalization 32 Techniques in Knee Surgery

6 Tibial Tubercle Osteotomy FIG. 4. Merchant radiograph. tibial tubercle surgery will play a role in the overall patellofemoral plan, a specific tubercle approach may be applied based on the indications section. TECHNIQUE As the various techniques under consideration have been described numerous times in the literature, only a brief overview will be followed by a summary of technique details. To aid in comparing these surgeries, an axial view is helpful (Fig. 6). Medialization The classic Elmslie-Trillat procedure of medialization as popularized by Cox 5 in the United States is largely unchanged today in concept. The lateral release portion of the procedure may be done arthroscopically, decreasing the length of the incision. The procedure may be performed using local anesthetic infiltration of the skin and periosteum. The longitudinal incision is made immediately lateral to the tibial tubercle beginning at the proximal patellar tendon attachment level and continuing distally approximately 6 to 8 cm. The subcutaneous tissues are elevated from the tubercle, and the anterior compartment musculature is elevated subperiosteally 1 cm posterior to the anterior crest of the tubercle. The proximal attachment of the patellar tendon is protected with an Army-Navy retractor and at 1.5-cm wide osteotome cuts from lateral to medial in the axial plane. Proximally, the flare of the tibia may make it awkward to make the next cut in the coronal plane, so a small portion of the flare may be trimmed, allowing a 2.5-cm osteotome to engage fully the lateral aspect of the tubercle 1.5 cm posterior to the anterior crest. The osteotome is directed lateral to medical with care to create a flat cut or one slightly oblique (resulting in a slight AMZ). The cut is completed medial to lateral while the distal attachment remains intact. With the 2.5-cm osteotome underneath the tubercle, a pair of pliers may aid in grasping and rotating the tubercle anteriorly, which creates an initial osteoclasis of the distal attachment. Then, direct thumb pressure completes the osteoclasis with medial movement of the tubercle. The knee is then placed through range of motion, and the movement of the tubercle is evaluated. At 90 flexion, the bony contour of the trochlea/notch will aid in positioning the tubercle more medially. The goal is to medialize to a more normal position, which is still lateral to the midline of the trochlea. This midline may be estimated by both palpation and inspection. The tubercle is temporarily fixed with a k-wire and then permanently fixed with two screws using the interfragmentary technique (directed medially with knowledge of neurovascular structures) (Fig. 7). Note that when performed in cases involving patellar subluxation, even though the patella may be central statically, it may still dislocate, and therefore, attention must be directed to the medial patellofemoral ligament system. Anteromedialization Fulkerson 12 has published a detailed description of his original techniques, which should be reviewed. Farr 11 modified the technique with the approval of Fulkerson. 12 The modification developed instruments for the surgery without changing the principles or bony cuts (Tracker AMZ instruments; Mitek, Norwood, MA). The procedure is preceded by a lateral release performed open or arthroscopically. The skin incision is from the level of the portals distally 15 to 20 cm. The subcutaneous tissues are elevated, and the lateral release is continued along the patellar tendon. Distal extension continues along the anterior attachment of the anterior compartment musculature. To allow freedom of tibial tubercle movement, an incision is made immediately adjacent to the medial border of the patellar tendon. At this point, a cutting block (in this example, the block does not have a rotating base piece 11 ) is applied to the anterior crest of the tubercle beginning at the medial border of the patellar tendon attachment and angled laterally in its distal course (Fig. 8). The obliquity of the jig will allow the distal cut of the tubercle to exit laterally, fully freeing the tubercle. If placed parallel to the crest, the cut would continue down to tibia. The desired slope of the osteotomy has been determined preoperatively. That is, the steeper the slope, the less medialization, and vice versa. The angle of the slope is visualized as the slope selector outrigger-aiming device is temporarily applied to the block. A custom retractor is placed posterior to the tibia and protects deep neurovascular structures after the anterior compartment musculature has been bluntly elevated from the lateral face of the tibia. The tip of the slope selector is placed posteriorly on the lateral face of the tibia. This predetermines where the osteotomy will exit. After fine-tuning the slope and planned cut exit, the cutting block is temporarily attached to the tibia with fixation pins placed Volume 2, Issue 1 33

7 J. Farr FIG. 5. (A) Patellar height measurement. (B) Lateral view comparisons of patellar position. through holes in the cutting block into drill holes in the tibia. An oscillating saw (irrigated) makes the cut, fully exiting posterior laterally under direct visualization (Fig. 9). The jig is removed. The distal cut is finished using the osteotomy as a saw guide distally. Proximally, an oblique cut is made from the proximal extent of the posterior cut to the lateral proximal attachment of the patellar tendon to the tubercle. The tubercle is fully released after a slightly oblique transverse cut is made from the lateral aspect of the patellar tendon proximal attachment to the medial side. The tubercle is now free (Fig. 10). In open cartilage restoration surgery, the tubercle and patella may 34 Techniques in Knee Surgery

8 Tibial Tubercle Osteotomy FIG. 6. Tubercle osteotomies, axial views compared. be reflected superiorly, fully exposing the trochlea and patellar surfaces. After the desired tubercle position is achieved, it is fixed with the interfragmentary technique. If the elevated medial border of the tubercle is sharp and impinging on soft tissue, it is trimmed with a rongeur (Fig. 11). Figure 12 demonstrates intraoperative elevation measurement. Anteriorization The classic anteriorization is the Maquet, which requires iliac crest bone graft. Multiple variations are available for review in the literature. Today, with documentation of a lower complication rate using the Fulkerson AMZ, the AMZ technique may be modified to effect anteriorization without medialization. The technique begins like a standard AMZ, except the slope is nearly vertical. To avoid cutting through the posterior tibial cortical bone, an additional (near coronal plane) cut is made just anterior to the posterior aspect of the tibia. An osteotome is inserted into this posterior cut so that the saw contacts the osteotome rather than penetrate the posterior cortex. Alternatively, first a standard AMZ cut is made, but it is an extremely steep slope. This is followed by harvesting a local corticocancellous block. This block is the thickness of the measured medialization component. By inserting the block between the tubercle and the tibial cut, the medialization is neutralized; thus, the procedure results in direct anteriorization (Figs. 5, 13). Anterolateralization Fulkerson reversed the slope of the AMZ with anterolateralization (Fig. 4). Care is taken not to injure the MCL or the pes anserine tendon group. Figure 14A demonstrates medial patellofemoral degenerative change after more than 10 years post-hauser in a patient with marked symptoms. Figure 14B shows the same patient s Merchant view 9 years after anterolateralization. The patient remains pain-free to the present. Volume 2, Issue 1 35

9 J. Farr FIG. 7. Tibial tubercle medialization. FIG. 8. Positioning AMZ cutting block. 36 Techniques in Knee Surgery

10 Tibial Tubercle Osteotomy FIG. 11. Fixed AMZ; rongeur trimming tubercle. FIG. 9. AMZ saw cut. Distalization As noted previously, distalization is most commonly used in conjunction with other patellofemoral procedures that are addressing recurrent patellar instability in which there is a component of patellar alta. The tubercle is approached as per the medialization technique above, but before the bony cuts are made, a saw is used to make two distal cuts. The distal cut is made where the tubercle will be transferred with distalization. Just proximal to this cut, a second cut is made. The distance between the cuts delineates the amount of distalization that will occur (Fig. 15). The goal is to normalize the patella height, not to overcorrect it. If medialization is also desired, the more proximal cut is made slightly obliquely such that when reduction occurs, the tubercle cut fits flush with the tibial cut (the obliquity takes into account the rotation of the tubercle and may be modified as the amount of rotation is evaluated intraoperatively). During evaluation of the final position, a tubercle drill hole is made, through which a k-wire is inserted. This can allow rotation of the tubercle even as it is abutted to the tibia with distalization. Final fixation is performed with two interfragmentary screws. Figures 16, 17, 18, and 19 show preoperative and postoperative radiographs in which minor distalization was used in conjunction with medialization of the tubercle performed to centralize the FIG. 10. Measuring tubercle elevation. FIG. 12. Intraoperative AMZ elevation measurement. Volume 2, Issue 1 37

11 J. Farr FIG. 13. Bone block offset of AMZ to effect straight anteriorization. chronic patellar subluxation statically in a patient with recurrent lateral instability. Note that with these two components completed, it was still possible to dislocate the patella laterally; thus, at the same setting, the medial patellofemoral ligament was reconstructed. The thought process was that the medialized quadriceps vector (through medialization) would stress the reconstruction less. Proximalization Proximalization is only one part of a more extensive surgery to address the patella infera of arthrofibrosis. The FIG. 14. (A) Preoperative ALZ (post-hauser medial PF degenerative change). (B) Nine years postoperative ALZ. FIG. 15. Distalization of tibial tubercle. arthrofibrosis surgery and patellofemoral chondrosis will dictate whether the approach is through an AMZ or straight medialization technique (in this situation, the distal attachment would be cut rather than using osteoclasis). Once the tubercle is prepared, two (of many) options are presented for proximalization (Fig. 20). In the first, the channel is cut more proximally in the tibia, paralleling the distal cut. This allows the tubercle to slide proximally. This does alter the patellar tendon angle, and if performed with AMZ, it is limited by potential bony impingement of the tubercle on the roof of the notch/distal trochlea. These limitations may be addressed by skeletonizing the proximal tubercle, as the patellar tendon tubercle attachment is more extensive than just the proximal leading edge (Minas, Personal communication, June 2002). The tendon may be stripped approximately 1 cm, and that portion of stripped bone may be resected. The remaining tubercle is then proximalized to the limit of the original tubercle cut. Extreme caution must be exercised in evaluating the soft tissues and how they might respond to such tampering in light of the underlying disease process. Interfragmentary fixation secures the tubercle. RESULTS As is obvious, the tubercle is only one part of a comprehensive approach to the patient with patellofemoral prob- 38 Techniques in Knee Surgery

12 Tibial Tubercle Osteotomy Each of the tubercle procedures carries with it unique complications. In general, as with all patellofemoral procedures, a common complication is that of a technically correctly performed surgery, but with an unhappy patient. Patient selection and counseling to assure the patient has realistic expectations cannot be overemphasized. Intraoperative complications may involve neurovascular structures and should be avoided through proper retraction and knowledge of the anatomy. Postoperative complications are similar to those of any knee surgery, including infection, arthrofibrosis, complex regional pain syndrome (previously referred to as RSD), thromboembolism, malunion, nonunion, failure of fixation, and fracture. Arthrofibrosis has many causes, but with the secure fixation of the above surgeries, early motion and patellar mobilization are stressed as an attempt at decreasing this problem. Fracture is avoided by FIG. 16. Preoperative distalization plus medialization (lateral radiograph). lems. Thus, there are no truly isolated tibial tubercle results, and the reader should review specific treatments for specific diagnoses. There remains no uniform consensus on how and when to apply these techniques, and the Hauser late failure should temper enthusiasm for any perceived cures. On the other hand, the literature listed in the historical perspective section shows that with attention to detail, good and excellent results are possible. In the case of the AMZ, Buuck and Fulkerson 14 has found that the initially reported good results are holding with long-term follow-up (Figs. 20,21,22). As further results are reported, it must be remembered that patient selection and surgeon individual technique may be other confounding variables when trying to apply science to this complex subject. COMPLICATIONS FIG. 17. Postoperative distalization plus medialization (lateral radiograph). Volume 2, Issue 1 39

13 J. Farr FIG. 18. Preoperative distalization plus medialization (Merchant radiograph). protected weight bearing up to 6 weeks with the extensive bony cuts of an AMZ. Specific to the patella is that the very musculature (quadriceps) most important in rehabilitation is in line with the surgery. This complicates re-establishment of muscle strength and balance. Profound atrophy may be difficult to reverse. Certainly, the goal is to avoid multiple operations on the knee. Careful planning can help to achieve this goal of accomplishing the desired end result at one setting. A case in point is the lateral release. It is not a small surgery in terms of the effect on the joint. It should not be cavalierly used as a first step to see if it helps. If tubercle surgery is indicated after initial evaluation, then a comprehensive single staged surgery is less traumatic to the knee than two surgeries. In many patients, the surgeon gets only one chance to make them better. Long-term complications may be related the articular surface, which has a limited range of stress acceptance before degeneration occurs. It is important to follow patients, as the articular cartilage deterioration may take several years. This may be done remotely through a web-based outcome study such as available at In addition, any evidence of cartilage abnormality at the time of surgery deserves either close follow-up or possible consideration for cartilage restoration. protected with respect to the extent of bony surgery, and all weight bearing must be done with a normal gait. Home exercise is begun immediately. If quadriceps shutdown occurs, rapid quadriceps re-education is initiated with biofeedback and functional electrical stimulation. In light of the complex nature of the patellofemoral patient, early use of a physical therapist expertly trained in the art and science of the patellofemoral joint is essential. The current advances in therapy techniques address the entire kinetic chain and do not cookbook the rehabilitation program. To monitor this program, the patient is usually evaluated in the office every 1 to 2 weeks for the first month, and bony healing and alignment is checked radiographically at 6 weeks. If gait is normal, pain is resolved, and strength is nearing normal, patients may be released to remote follow-up (e.g., at 8 to 12 weeks. CONCERNS/FUTURE OF TECHNIQUE The major concern for the present techniques is that they are based on clinical observation and the theory of malalignment. Some patellofemoral surgeons even question if there is such a thing as malalignment. These surgeons serve as the conscience of realigning surgeons to first, do no harm. The lesson of the Hauser procedure should never be forgotten. Even subtle changes in stress to a 20-year-old knee may have serious consequences over the next 70 years of life. With these concerns in mind, one of the first steps is to return to basic science and to repeat the force and contact area work previously performed, but using newer technology with an appreciation of the total dynamics. On the clinical front, prospective analysis is needed to allow finally objective quantification of malalignment and how it relates to procedural selection and patient outcome. With this data, ideally there can be some consensus among patellofemoral surgeons as to what malalignment is and how this should direct surgery. This is under ongoing continued POSTOPERATIVE MANAGEMENT Many of the tubercle surgeries may be performed on an outpatient basis, but in the case of more extensive or concomitant surgeries, hospital admission for pain control and initiation of rehabilitation is appropriate. If there is a concern for a marked fibroblastic response, continuous passive motion is added. To facilitate early motion and rehabilitation, salvage and more extensive procedures may be performed using an epidural, which is continued for 2 to 3 days postoperatively while the patient is gradually weaned to oral medication. Weight bearing is FIG. 19. Postoperative distalization plus medialization (Merchant radiograph). 40 Techniques in Knee Surgery

14 Tibial Tubercle Osteotomy FIG. 20. Proximalization of tibial tubercle. review inspection by the International Patellofemoral Study Group ( In addition to radiographic and clinical follow-up, recent advances in cartilage research will allow less invasive monitoring of the status of the articular cartilage. Included in these techniques will be MRIs with improved cartilage specific sequencing and improved sensitivity with enhancing agents (such as the postexercise gadolium studies used today). This may be expanded with position emission biochemical scanning. The byproducts of patellofemoral articular cartilage degradation may be monitored by washout aspiration (blood or urine samples) if only one joint is involved. Certainly, early detection of cartilage injury will ideally avert untoward sequelae from surgery and may suggest earlier intervention in cases where symptoms alone would not suggest intervention. From a technique standpoint, if and when there is agreement as to the quantification of the degree of malalignment, realignment can be directed more objectively. At that point, realignment may be precisely guided aided with three-dimensional computer analysis, which is in limited use for guiding tibiofemoral realignment and for cuts in total joint arthroplasty. This may also allow monitoring of contact areas during range of motion, and when used with intraoperative force transducers, it is possible that stress in the articular cartilage could be calculated through range of motion. The goal would be to keep this stress within the physiologic range in an attempt to optimize cartilage longevity, patient comfort, and function. FIG. 21. Preoperative AMZ (Merchant radiograph). FIG. 22. Nine years after AMZ (Merchant radiograph). Volume 2, Issue 1 41

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