Distal Femoral Osteotomy - Dissertation Example

?Distal Femoral Osteotomy Introduction Distal femoral osteotomy is a surgical procedure aimed at correcting deformity in the lower limb. This entailsthe treatment of osteoarthritis of the lateral compartment of the knee apart from the correction of valgus deformity (Wang and Hsu 2006). This chapter discusses when and why such a surgery is needed, the types of distal femoral osteotomies, and pre-operative procedures. It also succinctly describes the surgical procedure of distal femoral osteotomy. The chapter concludes with the post-operative management techniques and rehabilitation protocols followed after the osteotomy is performed. Need for Distal Femoral Osteotomy Femoral osteotomy is a highly convenient treatment for limb deformities in patients. Angular deformities can occur in the distal femur either in the developmental stages or through mal-alignment acquired later on. These are found in patients suffering from fracture malunion, osteoarthritis, metabolic disorders, adolescent-onset Blount disease or idiopathic processes (Seah et al. 2011). The axial alignment of lower limbs is affected by limb deformities, and is of immense concern when mechanical forces occurring during ambulation influence the articular cartilage. The varus and valgus alignment of the knee, when investigated through biomedical studies, have been shown to increase the medial and lateral load, thereby resulting in the progression of osteoarthritis. Studies have shown that degenerative valgus deformities of the knee are less frequent than varus deformities (Wheeless 2012). In order to treat these deformities, the angle between the femur’s anatomical axis and the tibia’s mechanical axis has to be corrected up to 0-2° of valgus. This procedure will result in the unloading of the lateral tibio-femoral joint compartment, thus preventing the deformity from reoccurring. For the treatment of genu varum, high tibial osteotomy has been used successfully (Wheeless 2012). On the other hand, it is found to be less effective in case of genu valgum as it results in the formation of an oblique joint line. The tilting results in the generation of shear force across the knee, apart from lateral tibial subluxation, wherein the distal femur seems to fall off the plateau of the medial tibia. In such an instance, distal femoral osteotomy is apparently a better treatment option. Shoji and Insall (cited in Paddu et al. 2009), who studied 49 patients through a 31 month follow up, showed that only 26 of the 49 patients who had had proximal medial tibial closing wedge osteotomy had total relief from pain. Only seven of the patients had partial relief while sixteen had no relief at all. As already described, this treatment has been ineffective because when a major deformity in the valgus is corrected, the joint line slopes in the frontal plane superaolaterally. If the angle between the tibial mechanical axis and the anatomic femoral axis is more than 12-15° of the valgus, or if there is a deviation of the joint plane by more than 10° from the horizontal, distal femoral osteotomy is indicated. This specification was given by Bouillet and Van Gaver (cited in Paddu et al. 2009). A number of other studies have also suggested that osteotomy in the distal femur should be performed rather than in the proximal tibia if the angle between the tibia and femur is more than 12°. Another study by Maquet (cited in Paddu et al. 2009) has provided evidence that distal femoral osteotomy is a better treatment option for valgus deformity in patients as it helps in restoring the lower extremity’s mechanical axis, thereby reducing the Q angle and biomechanically altering the patellofemoral joint. Phillips and Krackow (1999) have suggested that this feature is an additional benefit as valgus malalignment is usually associated with patellofemoral disorders. In presence of restricted motion of the knee or inflammatory arthrititides, distal femoral osteotomy is contraindicated (Wheeless 2012; Distal Femoral Osteotomy 27450 2012). Preoperative Planning Before performing an osteotomy, it is essential to perform a detailed physical examination and record the patient’s history (Anbari 2009). The patient’s history should include his activity level, his occupation, surgical and non-surgical interventions performed earlier, and the frequency of pain. The surgeon also needs to review the radiographic and arthroscopic images taken previously, if any. A standard physical examination, assessment of the patient’s habitus and examination of alignment should be done apart from investigating any rotational, sagittal or coronal instability. A typical standard evaluation in preoperative planning involves the examination of the alignment of the lower limb through radiographic imaging. Radiographic imaging can be performed in four views, namely –merchant, lateral, standing anteroposterior (AP), and 45-degree flexion posteroanterior (PA) (Anbari 2009). Magnetic resonance imaging or computed tomography is not generally recommended, however, Paddu et al. (2009) suggest that the subchondral bone’s stress reaction, which can only be detected through magnetic resonance imaging, may be the only indication of the early stage of a degenerative process. The degree of correction in coronal and sagittal plane also has to be calculated. The measurement of the mechanical axis is highly essential. This is done via a straight line drawn from the femoral head’s center to the talus center. This is helpful in tracking the weight across the knee joint. Dugdale et al. (1992) have succinctly described the method of pre-operative planning prior to osteotomy. Accordingly, the weight bearing line is aligned in position 50% across the tibial plateau. The correction angle between the line from the femoral head’s center to 50% of the tibia and the line from the talus’ center to 50% of the coordinate is taken. The width of the femur can be measured and the wedge size can be decided based on the angular correction. Distal femoral osteotomy can then be performed. Operating Procedure Types of Distal Femoral Osteotomy Osteotomy of the distal femur can be performed in two ways. One is the lateral wedge opening osteotomy and the other is the medial wedge closing osteotomy (Sternheim, Garbedian and Backstein 2011). The medial closing wedge osteotomy of the distal femur is carried out on the medial side, near the adductor tubercle and femoral articular surface. A two-third wedge is taken from the supracondylar area to create a stable construction. In this process, the lateral cortex is left intact and the osteotomy is culminated with a 90° blade plate. Stability for mobilization is provided with the help of a 90° plate with offset. In this type of osteotomy, a precise bone has to be removed, and thus, it requires a more precarious approach (Paddu et al. 2009). The open wedge osteotomy on the other hand is performed laterally. AO 95° angled plate is the most commonly employed fixation device used in this technique. A simple set of instruments and plates are employed during surgery. A plate with a tooth like spacer, which is available in various sizes ranging from 5 to 17.5?mm is used in this procedure. The plate is inserted tooth first into the osteotomy line for preventing the collapse of the bone that may have otherwise resulted in recurrence of deformity. The spacer thickness depends on the desired corrected angle. The other plates used in this kind of distal femoral osteotomy are shaped in the form of a T, with four proximal and three distal holes relative to the tooth. Titanium alloys are used in the second generation plates. They have special screw holes in which screws can be lodged. A jack opener is used for facilitating the osteotomy procedure. A wedge opener, an important tool in this surgery, is inserted into the osteotomy for measuring the opening wedge. The wedge opener device appears like a fork with two wedge shaped tines for facilitating measurements. It also has a removable handle to enable the positioning of the plates. Another tool, which is a rod guide, is also used. This tool offers ankle support for intraoperative maintenance of the new alignment. Surgical Procedure Some surgeons prefer to perform distal femoral osteotomy with the help of a pneumatic thigh tourniquet, which however is not necessary (Tolo and Skaggs 2008). In the absence of a tourniquet, fluoroscopy is used to locate the distal femoral physis that is generally located at the junction of the patella’s mid and proximal thirds. A brief description of the surgical procedure of distal femoral osteotomy in children, as given by Tolo and Skaggs (2008) is given here: Firstly, a longitudinal incision that is approximately 4-5 cm long is made laterally. Care is taken to keep the distal end of the incision at physis level. The iliotibial band is incised and the distal femur is reached through a subvastus approach. It is easier to do this in the distal to proximal direction. The vastus can be mobilized off the intermuscular septum with the help of electrocautery. Perforating vessels that are encountered during the process should be carefully cauterized. The osteotomy site can be localized with fluoroscopy. A metaphysical osteotomy facilitates early recovery because of the better healing capacity and larger cross-sectional area of the metaphysis when compared to the diaphysis. A subperiostal dissection also has to be carried out. This is done by placing two derotation pins through the incision. The pins are placed parallel to one another and the physis. One pin is placed proximally and the other distally to the osteotomy site in order to ascertain the amount of rotation throughout surgery. Once the pins are placed, the femur is osteotomized with an oscillating saw parallel to the physis and perpendicular to its long axis. The posterior structures are protected with the help of a large elevator. Care should be taken to avoid the neurovascular structures while the saw is being used on the posterior femur. During the osteotomy, osteotomes may also be employed if needed. The proximal fragment is secured with a bone holding clamp and then, the distal fragment is rotated. This is easier to perform if the knee is flexed by 90° and the lower tibia is grasped so as to achieve enough lever arm for rotation. Higher degree of translation in the sagittal and coronal planes should be avoided. The angle of derotation can be estimated by measuring the angle between the two derotation pins that were parallel earlier. This is done with the help of a sterile goniometer. Fixation is achieved with the help of K-wires. Two or three pins are inserted from the metaphysis, exiting from the metadiaphysial junction. As already discussed, distal femoral osteotomy is performed either as opening wedge or closing wedge. The surgical procedure of these two kinds of osteotomies in adults is briefly described in the next section. Surgical Procedure for Opening Wedge Distal Femoral Osteotomy: This osteotomy involves a lateral approach. The patient is placed in a supine position and a tourniquet may be used. Prior to closure, the tourniquet may be deflated in order to ensure proper hemostasis (Anbari 2009). The iliotibial band’s posterior edge is first palpated and a 2cm incision is made on its anterior. The iliotibial band is then split and the vastus lateralis is lifted to expose the metaphysis and the femoral shaft. Care should be taken to cauterize or ligated any perforating vessels. Following this, a guide pin is inserted. The position of the pin is proximal lateral to distal medial. The exit point of the pin should be around the medial epicondyle. The osteotomy cut is then performed perpendicular to the femur in order to prevent flexion of the distal fragment. A second pin is then placed parallel to the first guide pin. A bovie wire is placed, with the help of fluoroscopic guidance, on the thigh. It is positioned from the center of the head to the ankle joint’s center. Osteotomy distraction is then performed. The final step is plate fixation. After the desired angle of correction is achieved, the plate is fixed with unicortal cancellous and bicortal screws (Anbari 2009). Surgical Procedure for Closing Wedge Distal Femoral Osteotomy: For this osteotomy, the patient is placed in the supine position (Sternheim, Garbedian and Backstein 2011). An inflated tourniquet may be used. A 15cm long midline incision is made from distal to proximal joint line and the vastus medialis muscle is dissected bluntly from the medial intermuscular septum. This is done to expose the medial femoral condyle and the femoral cortex. The knee is flexed by an angle of 90°. With the help of arthrotomy, a guide wire is passed parallel to the articular femoral surface. Another guide wire is then drilled proximal to the femoral articular surface into the medial femoral condyle. This wire is parallel to the first guide wire. This is a critical step in the correction of the deformity. It aligns the femur’s anatomical axis perpendicular to the blade plate and the articular surface of the femur. Following this, three holes of 4.5nm are drilled into the medial femoral cortex and the anterior of the medial cortex. The holes are meant for the incorporation of the blade plate chisel and for the prevention of uncontrollable fracture in the femur. At a 1cm distance from the chisel, a closing wedge osteotomy is made. An osteotomy saw is used to make the base of the osteotomy and the lateral cortex is perforated using a drill bit and osteotome. This is done to facilitate the correction of the deformity without translocating the proximal fragment. At least 5-10 nm wide base of the wedge is required so that a 90° angle can be obtained between the medial femoral cortex and the chisel after the removal of the wedge. A dynamic compression plate is then inserted. The bony wedge created through osteotomy is morselized and used as an autograft. With the help of standard compression techniques, screws are inserted into the compression plate. The transepicondylar femoral line and the femoral cortex’s medial part are now at an angle of 90° relative to one another. In this osteotomy, a 0° anatomical tibiofemoral angle is achieved (Sternheim, Garbedian and Backstein 2011). Post-Operative Management Procedures of the distal femur usually result in loss of ROM (range of motion) when resting with extended leg (Lobenhoffer and van Heerwaarden 2009). Therefore, after surgery, immediate leg positioning in near 90° knee flexion and 90° hip position is recommended. In children, a long leg cast is placed during surgery and weight bearing is allowed 3-4 weeks post op (Tolo and Skaggs 2008). The pins are removed and the cast is changed 4 weeks post op. Until the bone is completely healed, casting is continued 2 months post op. In adults operated with closing wedge distal osteotomy, active flexion of the knee generally begins 10-14 days post op and weight bearing is allowed 6-8 weeks post op (Sternheim, Garbedian and Backstein 2011). If uniting of the osteotomy is observed in radiographs, weight bearing is allowed. The patients generally resume full activity 6 months after surgery (Puddu et al. 2009). Rehabilitation Protocol The rehabilitation protocol is usually divided into four phases: phase I (0 to 4 weeks), phase II (4 to 6 weeks), phase III (6 weeks to 3 months), and phase IV (3 to 9 months) (Anbari 2009). Once the surgery is complete in distal femoral osteotomy, the knee is immobilized using a brace (Puddu et al. 2010). The ROM brace is placed in full extension or a 10° flexion is allowed. Extension in a CPM is allowed a day after the surgery. Patients can walk without weight bearing two days after surgery. Patients are discharged 3-4 days post-op when the effusion and pain are minimal. Strengthening exercises and rehabilitation procedures are then commenced. In phase I of post-operative management, touch-down weight bearing with crutches is acceptable until 6 weeks post-surgery. Patients have to wear the brace at all times except while using CPM (continuous passive motion) machine. Four hours per day, CPM can be used for achieving 90° flexion during the first three weeks. Physical therapy is also employed for early recovery. This involves the use of ankle pumps, quadriceps sets, calf or hamstring stretches (nonweight bearing), straight leg raises, etc. In the second phase, weight bearing can be done without the help of crutches if X-ray indicates adequate healing. During ambulation, brace can be unlocked. If knee flexion reaches 90°, CPM machine can be discontinued. Physical therapy is continued with straight leg raises. Once the patient is free from pain, the brace can be discontinued in the third phase. Physical therapy can be continued with the commencement of mini-squats at 0-45°, leg press at 0-60°, balance activities, knee extension and toe raises. In the fourth phase, closed-chain terminal knee extension exercises can be continued as tolerated. Treadmill walking can be initiated and progressed as tolerated by the patient. By the end of this phase, the patient can resume normal activity. Post-Operative Instructions for Patients Proper care has to be taken with respect to diet, wound care, medication, activity and exercise. Patients should begin with light foods such as soups and jellos along with clear liquids (Cole 2003). Patients can proceed to a normal diet if they are not nauseated. The surgical incisions must be kept clean and dry to avoid infection. The operative leg should not be immersed in water. To reduce swelling, the operative leg can be raised to chest level when possible. Pillows should not be placed under the knee but can be placed under the ankle or the foot. The knee should not be maintained in a bent or flexed position. Walking can be done with the help of crutches. Patients should not engage in activities that result in pain and swelling in the knee at least 7-10 days post-surgery. It is also advised to avoid long distance travelling or sitting without leg elevation until two weeks. Patients are also advised not to drive. If pain is tolerable, the patient can return to sedentary activities 3-4 days post-surgery. The brace needs to be worn extended at all times. It can be removed for knee flexion in order to exercise in a non-weight bearing position. Braces are removed when CPM machine is used (Cole 2003). Ice therapy can be employed immediately after surgery every two hours daily, for twenty minutes, with the leg kept elevated at chest level. CPM machine use can commence the first day after surgery. It can be used out of brace for 6-8 hours a day in increments of two hours. The machine use can commence at the rate of one cycle per minute, beginning with extension to flexion by increasing the flexion by 5-10° every day. Patients are advised to limit the flexion only up to a comfortable level, with 90° being the maximum. The exercises, which include quad sets, straight leg raises and ankle pumps can commence 24 hours post-surgery unless otherwise instructed by the surgeon or physician. The exercise can be done three-four times every day until the first post-op visit. Ankle pumps can continue throughout the day to prevent the formation of blood clots in the calf (Cole 2003). The Orthopaedic Research Clinic of Alaska comprehensively lists out the precautions, goals, and exercises for post-operative management of distal femoral osteotomy (Vermillion n.d.). It divides the post-operative time into four stages, namely – the immediate post-operative phase (0-4 weeks post-op), the late post-operative phase (4-8 weeks post-op), early rehabilitation (8-12 weeks post-op), and late rehabilitation (12-16 weeks post-op). In the immediate post-operative phase, NSAIDs should not be taken and the knee brace should be locked at 0°. End-range flexion should be avoided. Weight bearing is not permissible. The main goals of rehabilitation during this phase include pain control, contracture prevention, edema control, quad control, cartilage protection, and an ROM of more than 90°. For pain and edema control, manual lymphatic drainage can be performed, cool packs can be used, and the knee can be placed at an elevated level. Patella mobilization, quad sets, core strengthening and stabilization exercises can be performed. In the late post-operative stage, NSAIDs should be avoided, care should be taken to protect the patellofemoral joint, and patients should not engage in strenuous activities. The goals of the rehabilitation during this phase include edema control, gain of full ROM, normalization of gait pattern, and gain of normal strength. This can be achieved through elevation, cool pack, compression sleeve or use of TED hose, and manual lymphatic drainage as in the earlier phase. The patient can practice pool walking, and carry out low resistance exercise. Leg press at 0-60°, toe raises, and core strengthening exercises can be carried out. During the early rehabilitation phase, patients should avoid impact activities, contact sports and NSAIDs. The goal of the rehabilitation protocols in this phase is to attain the ability to walk, to enable full weight bearing, to be able to bike on level ground, and to attain full ROM. Exercises and activities to be done during this phase include low weight leg extensions and curls, stationary bike, step-ups, hamstring curls, kinetic chain strengthening, unloaded treadmill, core strengthening, side stepping and short arc quads. Once the patient’s physician indicates proper recovery, the patient can move on to the next phase of rehabilitation. In this phase too, NSAIDs should be avoided. The goals of the rehabilitation protocol in phase are to gain a normalized gait and to enable full weight bearing. The patient can cycle on level surfaces and can also engage in vigorous walking. Light jogging can be done at the end of the phase. Ice skating is permissible with brace. Open kinetic chain and closed kinetic chain exercises can be performed. Conclusion Various studies have investigated the efficacy of distal femoral osteotomy in the treatment of lower limb deformities. Wang and Hsu (2006) studied the result of distal femoral osteotomy in the treatment of genu valgum. They also evaluated the influence of patellofemoral arthritis on the treatment outcome of distal femoral osteotomy. They concluded that distal femoral osteotomy is a reliable procedure for treating lateral-compartment osteoarthritis of the knee. It was also found that the outcome of this osteotomy is not affected by patellofemoral arthritis. Nelson et al. (2003) investigated the outcome of knee arthroplasty after distal femoral osteotomy in a study group consisting of nine patients. The study showed that total knee arthroplasty after osteotomy helped improve knee function and reduce pain. However, they also showed that the procedure is demanding with respect to its technicality and the outcome was inferior to that of primary arthroplasty without femoral osteotomy. Sternheim, Garbedian and Backstein (2011) also showed that distal femoral medial closing wedge varus osteotomy is effective in unloading the lateral compartment. Several other studies have investigated follow-up of patients who underwent distal femoral osteotomy. Most studies have provided evidence of the efficacy of the process. This chapter discussed the surgical procedure and the post-operative rehabilitation protocols of distal femoral osteotomy in order to set the stage for further discussion on post-operative procedure and patient rehabilitation in the upcoming chapters. References Anbari, A 2009, ‘Proximal Tibial and Distal Femoral Osteotomy’, in Cole, BJ & Gomoll, A (eds.), Biologic Joint Reconstruction: Alternatives to Arthroplasty, Slack Incorporated, New Jersey, pp. 203-210. Cole, BJ 2003, Post Operative Instructions Distal Femoral Osteotomy, visited 1 January 2013, . Distal Femoral Osteotomy 27450 2012, viewed 1 January 2013, . Dugdale, TW, Noyes, FR & Styer, D 1992, ‘Preoperative planning for high tibial osteotomy’, Clinical Orthopaedics, vol. 274, pp. 248-264. Lobenhoffer, P & van Heerwaarden, R 2009, Osteotomies around the Knee: Indications-Planning-Surgical Techniques using Plate Fixators, Thieme, New York. Nelson, CL, Saleh, KJ, Kassim, RA, Windsor, R, Haas, S, Laskin, R & Sculco, T 2003, ‘Total Knee Arthroplasty After Varus Osteotomy of the Distal Part of the Femur’, The Journal of Bone & Joint Surgery, vol. 85, no. 6, pp. 1062-1065. Phillips, M & Krackow, K 1999, ‘Distal femoral varus osteotomy: indications and surgical technique’, in Zuckerman J (ed.), Instructional Course Lectures, Rosemont, Illinois, pp. 125-129. Puddu, G, Cipolla, M, Cerullo, G, Franco, V & Gianni, E 2010, ‘Which osteotomy for a valgus knee’, International Orthopaedics, vol. 34, no. 2, pp. 239-247. Puddu, G, Franco, V, Cerullo, G & Cipolla, M 2009, ‘Distal Femoral Osteotomy for Genu Valgus Correction’, Techniques in Knee Surgery, vol. 8, no. 4, pp. 257-264. Seah, KTM, Shafi, R, Fragomen, AT & Rozbruch, SR 2011, ‘Distal Femoral Osteotomy’, Clinical Orthopaedics and Related Research, doi-10.1007/s11999-010-1755-0, viewed 1 January 2013, . Sternheim, A, Garbedian, S & Backstein, D 2011, ‘Distal Femoral Varus Osteotomy: Unloading the Lateral Compartment: Long-term Follow-up of 45 Medial Closing Wedge Osteotomies’, Orthopedics, vol. 34, no. 9, pp. e488-90. Tolo, VT & Skaggs, DL 2008, Pediatrics, London, Lippincott Williams & Wilkins. Vermillion, DA n.d., Lateral Distal Femoral Osteotomy Rehab Protocol, visited 1 January 2013, < http://www.alaskabiosurgeon.com/documents/LateralDistalFemoralOsteotomyRehabProtocol.pdf>. Wang, J & Hsu, C 2006, ‘Distal Femoral Varus Osteotomy for Osteoarthritis of the Knee’, The Journal of Bone & Joint Surgery, vol. 88, no. 1, pp. 100-108. Wheeless, CR 2012, Wheeless Textbook of Orthopaedics, Duke Orthopaedics, Durham. Read More