Since Ilizarov proposed epiphyseal distraction for bloodless limb lengthening in 1969, the proximal epiphyseal bone scab distraction has been widely used clinically by surgeons for continuous improvement. However, the technique is very complex, involving nerves, blood vessels, articular cartilage, and skeletal muscles, and is also influenced by a variety of factors such as the patient’s own condition, the level of medical care, and the development of related disciplines [1], and its higher complications have been affecting its overall treatment outcome, prompting a re-evaluation and continuous improvement of the technique. The authors collected and analyzed 38 cases (54 limbs) in which lower limb lengthening was performed between 1992 and 2000, with the aim of exploring the clinical efficacy, complications and their prevention and control measures.
I. Clinical data
1. General data There were 38 cases in this group, 23 males and 15 females, aged 12-25 years old, average 16.4 years old, with follow-up time of 1-5 years, average 2.3 years. All 16 cases underwent bilateral proximal tibial osteotomy and lengthening due to short stature, with a preoperative height of 1.5-1.6 m in men and 1.4-1.45 m in women; 22 cases had unilateral limb lengthening, with limb shortening of 3.0-16 cm, including 7 cases of post-polio, 3 cases of osteomyelitis with epiphyseal destruction, 2 cases of postoperative congenital hip dislocation, 2 cases of post-Pethes disease, 3 cases of severe hip disorders, and 3 cases of cerebral palsy with limb damage. cases, 2 cases of cerebral palsy causing limb shortening, 1 case of congenital limb shortening, and 2 cases of giant tibial defect, with lengthening sites at the proximal femur in 6 cases, the middle femur in 3 cases, and the proximal tibia in 13 cases, respectively. (See Table 1)
Table 1 Distribution of 38 cases (54 limbs) of limb lengthening (limbs)
Disease or surgery name Proximal femur lengthening Mid femur lengthening Proximal tibia lengthening
Augmentation 0 0 32
Post-polio sequelae 0 0 7
Sequel of osteomyelitis 1 1 1 1
Postoperative congenital hip dislocation 2 0 0
Sequelae of Pethes disease 1 1 0
Sequelae of severe hip disorders 2 1 0
Sequelae of cerebral palsy 0 0 2
Congenital limb shortening 0 0 1
Large bone defect 0 0 2
2. Treatment Method Limb lengthening is performed according to Ilizarov’s biological principles, estimating the angular direction and lengthening degree, osteotomy at the stem or epiphysis of the long tubular bone, avoiding the vascular nerves, and paying attention to protecting the integrity of the epiphysis as much as possible when osteotomy is performed. The Ilizarov three-plane full ring (4 limbs), modified half-ring stainless steel ring (3 limbs) and unilateral combination external fixation frame (47 limbs) were selected to fix the broken ends of the osteotomy; when osteotomy of the upper tibial epiphysis was performed, the fibula was also cut in the upper middle third of the lower leg, and a Kirschner pin was penetrated at the distal end to prevent upward migration of the outer ankle. The lengthening was started at a rate of 1 mm/day, 2-4 times/day, with regular radiographs to observe the scab formation and healing, while paying attention to the correction of internal and external rotation or angular deformity. The lengthening will be stopped when the expected lengthening length is reached or when neurovascular crisis occurs, and the external fixator will be removed after 2-4 months of bone scab shaping and bony healing. At the time of debridement, the lengthening rod should be removed first, except for observation of new bone, and the patient should be debrided after about 3 to 5 days of no discomfort. The process of osteotomy lengthening of the middle femur and upper tibia is shown in Figure 1.
II. Results
The lower limb lengthening in the augmentation group ranged from 3.5 to 8.5 cm, with an average of 5.2 cm, and the lengthening index ranged from 27 to 38 days/cm, with an average of 31 days/cm; the unilateral limb lengthening group lengthened from 3.0 to 10.0 cm, with an average of 5.7 cm, and the lengthening index ranged from 29 to 42 days/cm, with an average of 33 days/cm. All cases achieved more satisfactory results 1 year after de-framing, with improved gait and limp, quality of life and self-confidence. (See Table 2)
Complications in lengthening included: joint stiffness, including 33 limbs of the knee and 17 limbs of the ankle; axial deviation, including 1 limb of the femur and 3 limbs of the tibia; early fusion of the bone ends, including 1 limb of the femur and 1 limb of the tibia; horseshoe deformity, 2 limbs of the tibia; ankle dislocation, 1 limb of the tibia; delayed healing, 3 limbs of the tibia; re-fracture, including 1 limb of the femur and 1 limb of the tibia; local infection of the pin tract, 46 limbs; and psychiatric depression, 1 case . All cases completed the extension program and no one abandoned treatment due to complications. (See Table 3)
Table 2 Results of limb lengthening in 38 cases (54 limbs)
Type of lengthening Number of cases (limbs) Age (years) Lengthening length (X±S, cm) Lengthening index (X±S, days/cm)
Unilateral lengthening 22 12 to 22 5.7±1.7 33±3.8
Augmentation 16 (32) 14 to 25 5.2±2.8 31±4.7
Table 3 Type and distribution of complications in limb lengthening (limb)
Complications Femoral osteotomy Tibial osteotomy
Joint stiffness (knee, ankle) 5 45
Axial deviation 1 3
Early fusion 1 1
Delayed healing 0 3
Re-fracture 1 1
Ankle dislocation 0 1
Horseshoe deformity 0 2
Pin tract infection 8 38
Psychological disorders 1 0
III. DISCUSSION
The Ilizarov technique allows surgeons to perform more daring design operations for congenital or acquired limb shortening, as well as a wide range of indications, using this method to manage a range of musculoskeletal system disorders, such as limb shortening, deformities and large bone defects can be reconstructed with bone [2]. Although there are still many problems with the Ilizarov limb lengthening technique, such as the complexity and length of the lengthening process and the increasing number of complications with the number of cases, the author believes that the application of this technique has increased the surgeon’s ability to challenge difficult orthopedic conditions, including cases of limb shortening combined with valgus or angular deformity, and cases where previous orthopedic treatment has failed, thus improving the quality of life and confidence of patients. This has improved the quality of life and confidence of patients and saved many limbs that would otherwise have had to be amputated due to osteochondritis, osteomyelitis or large bone loss.
1. Analysis of clinically relevant factors affecting the efficacy of scab retraction surgery
2. patient’s own factors Not surprisingly, age directly affects the surgical outcome of limb lengthening, with slower lengthening in older individuals and a significantly higher incidence of delayed healing in patients older than 20 years; studies have shown [2] that the lengthening index of the tibial epiphysis in children is approximately 0.87 months/cm, compared with 1.5 months/cm in adults. It is also found clinically that congenital or trauma-induced limb shortening deformity requires a longer period to achieve the desired effect; in addition, the cooperation between the patient and the operator and the subjective motivation of the patient are also factors that cannot be ignored.
3.Lengthening speed and retraction time The lengthening speed is one of the key factors affecting the bone evolution process of the repair tissue in the lengthening area.
Ilizarov recommends a lengthening speed of 1.0 mm/d to facilitate bone regeneration in the lengthening area. In fact, the lengthening speed varies depending on the conditions, for example, if the osteotomy is a dense bone with little blood flow, the lengthening speed should be slightly slower; in adults, the lengthening speed can be slightly slower, while in children, especially in epiphyseal osteotomies, the lengthening speed should be greater than 1.0 mm/d to prevent premature healing. It has been found that a lengthening rate of 0.5-2.0 mm/d is feasible for epiphyseal osteotomies, while a lengthening rate greater than 2.0 mm/d will exceed the local vascular regeneration capacity (especially for osteotomies in the diaphysis). Gao et al. found that the lengthening area was extremely vascularized and grew in parallel with the lengthening rate (1.0 mm/d) [3], and gradually diffracted to the normal cortical bone vascular system with the appearance of new bone cortex in the lengthening area; moreover, continuous slow pulling after osteotomy can apply axial tensile stress to the forming bone scab, stimulating cell proliferation and metabolic activity to obtain complete bone healing. Attention should also be paid to the appropriate lengthening frequency to avoid premature healing of the osteotomy area while ensuring that the blood flow to the broken end is not affected; the surrounding soft tissues should also be taken into consideration, and although the peripheral nerves can still tolerate a lengthening rate of 1.0 mm/d, they may not adapt to the muscle tissue. Clinically, limb lengthening is generally performed at a frequency of 2 to 4 times/day, and patients rarely feel discomfort, while regeneration of new bone is more satisfactory. In addition, because the transverse osteotomy blocks the endosteal blood vessels, a waiting time of 7 to 14 days (depending on the patient’s own factors and the condition of the bone) is needed to wait until the local trauma reaction subsides and blood circulation is restored before performing bone scab retraction, which is beneficial to the bone healing in the lengthening area.
4.Osteotomy site At present, we mostly choose epiphyseal or diaphyseal osteotomy, the slow stretching of the osteotomy area can
The repair is accomplished in three ways: endostealization, endochondralization, and direct osteogenic healing of the broken bone end [4]. Epiphyseal osteotomy lengthening is currently the most used method, especially the upper tibial epiphyseal osteotomy lengthening is often preferred, which is characterized by rich local blood flow, large bone contact surface, strong osteogenic ability and innate stability, and thin cortex for easy osteotomy. The femur lengthening can be chosen as the middle osteotomy, because there is no obvious lack of blood at its broken end, which does not affect the bone regeneration in the osteotomy area, and no complications such as bone delay, bone discontinuity and osteomyelitis were found; in this group of cases, the middle osteotomy lengthening of the femur was up to 10.5 cm.
In the process of bone lengthening, the blood supply of the broken end is directly related to the success or failure of the operation.
Ilizarov called the osteotomy of cortical bone as “low energy osteotomy”, meaning that the operation should be performed carefully to preserve the local periosteum and the blood supply to the medullary cavity as much as possible. However, preserving the medullary blood supply intraoperatively is difficult and the need for it is uncertain; most authors believe that the periosteal blood supply is critical for bone regeneration and that rough handling or extensive stripping of the periosteum during surgery will delay bone healing. The key to this procedure is to protect the outer periosteum intact, which is conducive to the growth and shaping of the bone scab, and to make the scab less likely to be deformed during distraction.
6. Choice of limb lengthening device The type of fracture healing and the remodeling process are related to the stiffness of the fixation device. A stable brace that does not affect adjacent joint motion, allows weight bearing, and preserves the physiological function of the limb provides good mechanical and biological conditions for fracture healing and functional recovery. Different external fixation scaffolds have their own biomechanical properties that affect bone regeneration and healing; and the stability of the scaffold is governed by multiple factors such as the number and diameter of the puncture pins, tension and fixation direction [5].The Ilizarov 3D external fixation scaffold undoubtedly has better biomechanical properties, and the tension kerf pins and ring external fixation frame ensure strong fixation of the broken end, thus creating a good bone healing The external environment is good for bone healing; however, the brace is bulky and often brings more inconvenience to patients after surgery. With the continuous improvement of technology, the unilateral combination of external fixation brackets can now also provide sufficient stability to achieve satisfactory results by avoiding to a considerable extent the unfavorable factors affecting healing and damaging the blood supply. The choice of clinical external fixation bracket is mainly determined by the osteotomy site, the complexity of the disease, the operator’s habit and experience, for example, the upper femoral osteotomy extension is better fixed with a single-arm external fixation bracket, the combined angular deformity should be selected with a circular external fixation bracket, and patients with augmentation should choose a single-arm external fixation bracket, which is conducive to postoperative rehabilitation exercises and improve the quality of life as soon as possible.
Analysis of complications and their prevention
1. Muscle contracture and joint stiffness are the most common complications in limb lengthening. It has been confirmed that under the condition of tension at a certain speed and frequency, muscle tissue has regenerative function; however, if a certain limit is exceeded, it will lead to uncontrolled muscle tissue regeneration and contracture, resulting in limited joint flexion and extension and even stiffness [6]. When the femur is lengthened more than 5 cm, N cord muscle contracture can occur and produce a flexion deformity; when the tibia is lengthened more than 6 cm, it can produce a horseshoe deformity (two cases occurred in our group and were corrected after Achilles tendon lengthening). In addition, pin-piercing fixation is also an important factor affecting the function of the joint. Routine loading exercise is necessary to maintain normal joint function and maintain the internal environment, so strengthening the active and passive flexion and extension activities of the joint during limb lengthening is one of the most cost-effective measures; at the same time, the intermittent stress stimulation generated during limb activity has the effect of promoting bone healing [7]. During the lengthening of the limb, especially the large lengthening, the mobility of the knee and ankle joints of patients decreases, but the joint function can be greatly improved or restored through timely active or passive exercises during and after lengthening.
2. Axial deviation The imbalance of muscle force at the osteotomy, different osteotomy sites and bone types, and poor fixation of the external fixation frame are the main reasons for axial deviation. The proximal femur and distal tibia osteotomy tend to have inversion and anterior convexity offset, the middle femur osteotomy tends to have anterior convexity offset, and the proximal tibia osteotomy tends to have exostosis and anterior convexity offset. Preoperative detailed design, skilled anatomical knowledge and firm and stable external fixation after osteotomy are the basic conditions to maintain the axial direction to prevent angulation [8]; in addition, when placing the external fixation frame during surgery, the pin can be tilted 5-10o and fixed in the opposite direction where angulation may occur, and should be adjusted in time if axial deviation is found after surgery. In this group, 4 cases of angular deformity occurred, 1 case of proximal tibial exostosis and anterior convexity deformity was corrected by surgery; the remaining 3 cases were relieved to varying degrees by adjusting the external fixator hinge and extending the concave side faster than the convex side.
Early fusion was observed in 2 cases in this group, mainly due to overemphasis on preserving the blood supply resulting in incomplete osteotomy, slow lengthening speed and failure of the external fixator to achieve the standard of loosening and stretching. Therefore, intraoperative surgical operation should be standardized, a secure external fixation brace should be applied, and the lengthening plan should be tailored to the individual; at the same time, regular postoperative review and timely radiographs should be taken to understand the progress of lengthening. In addition, studies have shown that if the waiting period for lengthening exceeds 2 to 3 weeks, early fusion is likely to occur, especially in smaller children and epiphyseal osteotomies.
4. Delayed healing, bone non-union and re-fracture No cases of bone non-union were found in this group, but three cases of delayed healing occurred. Analysis of limb lengthening leads to delayed bone healing and bone non-union for many reasons, such as peeling off too much epiphyseal membrane during osteotomy, unstable fracture site, too fast traction, too short waiting time for traction after osteotomy and infection. In order to reduce the incidence of delayed healing and bone nonunion, we should avoid the vulnerable factors as much as possible, strictly review the system on a regular basis, close the contact between the doctor and the patient, and obtain the active cooperation of the patient. The method of promoting bone healing in bone lengthening is still being explored, and it has been suggested that axial compression and local micromotion can promote bone healing immediately after lengthening; at the same time, good nutrition and prevention of disuse osteoporosis during lengthening are also necessary to ensure. In addition, there were two cases of re-fracture in this group, which were caused by premature removal of the external fixation brace; the authors experienced that the bone lengthener should be removed with caution, and the lengthening rod could be removed first to allow the new bone to gradually adapt to the physiological stress under gravity, which is conducive to the reconstruction of bone trabeculae to see if they can withstand gravity.
5.Ankle dislocation In this group, the upper tibial osteotomy lengthening was complicated by external ankle dislocation in one case, the reason is
The lengthening failed to fix the lower tibiofibular joint, and the external ankle was dislocated by shortening due to insufficient lengthening of the fibula, which was found to be a one-time lengthening of the distal fibula and repositioning of the external ankle. During surgery, screw fixation of the distal tibiofibular should be ensured, and if necessary, a review of the film should be taken so that the traction force acts equally on the distal tibiofibular through the bone round pin and the lengthening speed is synchronized.
6. Psychological barriers Ilizarov limb lengthening technique is quite complicated, time-consuming and often affects
The lengthening surgery is for the aesthetic appearance of their own image, so the whole process is prone to psychological barriers [9]. Patients and their families should be fully informed of the problems they may encounter during surgery and rehabilitation before surgery, and attention should be paid to regular communication with patients during the lengthening process to jointly face and deal with various unfavorable situations in a timely manner, and psychotherapy can be used when necessary. While eliminating the psychological barriers, the positive cooperation of patients will be obtained, which is conducive to early functional exercise and satisfactory results.