Case Report https://doi.org/10.14517/aosm16016 pissn 2289-005X eissn 2289-0068 Revision surgery for recurrent lateral patellar dislocation despite proximal realignment: a report of three cases You Keun Kim, Hyung Mook Lim, Min Joon Oh, Jae Doo Yoo Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea To remind physicians of the importance of thorough preoperative planning, we reviewed 3 cases of recurrent lateral patellar dislocation despite proximal realignment. The purpose of this study was to evaluate the reasons for the recalcitrant dislocations and to report the outcomes of the revision surgery. This study describes retrospectively a series of 9 cases consisting of patients who underwent revision surgery for recurrent patellar dislocations in spite of a previous treatment of proximal realignment. The following 5 pairs of revision-initial surgery were performed among our 9 patients to treat the recurrent patellar dislocations: (1) trochleoplasty after medial patellofemoral ligament repair in 1 patient; (2) tibial tuberosity transfer after medial patellofemoral ligament reconstruction in 2; (3) tibial tuberosity transfer and medial patellofemoral ligament reconstruction after medial patellofemoral ligament repair in 3; (4) medial patellofemoral ligament reconstruction after lateral release and medial imbrications in 2; and (5) tibial tuberosity transfer, medial patellofemoral ligament reconstruction, and distal femoral varization osteotomy after arthroscopic lateral retinacular release and medial imbrications in 1. Making detailed preoperative evaluations is very important when planning surgeries of recurrent patella dislocations. In light of our experience, the most common cause of recurrent patellar dislocations was inadequate preoperative planning, which leads especially to underestimation of the tibial tuberosity-trochlear groove distance. Keywords: Recurrent lateral patellar dislocation; Proximal realignment surgery INTRODUCTION A recurrent lateral patellar dislocation is one of the most common knee disorders in children and in adolescents [1,2]. It predominantly affects young adults, particularly women in their second or third decade of life [3]. Patellar instability is the resulting phenomenon of recurrent lateral patellar dislocation and several etiologies of the instability have been suggested, such as trochlear dysplasia, medial patellofemoral ligament insufficiency, increased Q-angle, patella alta, increased tibial tuberosity-trochlear groove (TT-TG) distance, vastus medialis obliquus muscle weakness, and valgus malalignment [4]. The management of recurrent patellar instability is difficult for many reasons, for example, on account of the heterogeneity of the demographic characteristics of patients, a multifactorial etiology of the condition, a lack of a gold standard surgical technique, and a lack of long-term clinical outcome studies related this condition [5]. The recent trend has seen a decrease in the use of long-term conservative management and an increase in early surgical management for patellar instability, especially for patients whose initial conservative management had failed. Although, many surgical procedures have been described to treat it, the optimal procedure remains to be determined and, currently, the general preference varies from one country to another. Further, various criteria have also been proposed to guide the choice of surgical procedure; elements of the criteria include patellar height, trochlear dysplasia, lateralization of the tibial tuberosity, patellar mobility, and patellar tracking [6]. Because the etiology of recurrent lateral patellar insta- Arthroscopy and Orthopedic Sports Medicine AOSM Received November 30, 2016; Revised December 20, 2016; Accepted December 21, 2016 Correspondence to: Jae Doo Yoo, Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital, 1071 Anyangcheon-ro, Yangcheon-gu, Seoul 07985, Korea. Tel: +82-2-2650-6142, Fax: +82-2-2650-0349, E-mail: koreanknee@gmail.com Copyright 2017 Korean Arthroscopy Society and Korean Orthopedic Society for Sports Medicine. All rights reserved. CC This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 28 Arthrosc Orthop Sports Med 2017;4(1):28-33
bility is heterogeneous, it is all the more important to understand their exact cause when preoperatively planning. The rate of recurrent dislocation after nonoperative treatment for patellar instability has been shown to be up to 80% and after surgical treatment, up to 40%. Despite such unpromising treatment outcomes, the number of studies that have investigated the cause of the failed treatment or the outcomes of revision surgeries of these recalcitrant knees is meager. To this end, this study describes three cases of revision surgery for recurrent lateral patellar dislocation despite proximal realignment, investigates putative reasons for the recurrent dislocations, and evaluates the outcomes of the revision surgery. CASE REPORTS This study was performed in two stages. The first part of the study involved an analysis of the sample of patients who had undergone only proximal realignment before presenting with a recurrent patellar dislocation. We identified a total of 51 knees (50 patients; gender ratio, 36 women to 14 men) with recurrent patellar instability after proximal realignment that had been performed by a single surgeon (J.D.Y.) between March 2002 and March 2014 at Ewha Womans University Mokdong Hospital (Seoul, Korea). Arthroscopic lateral retinacular release and medial imbrication had been performed on 20 knees, and medial patellofemoral ligament reconstruction had been performed on 31 knees, of which 22 had undergone simultaneous lateral retinacular release. The second part of the study involved an assessment of patients who after proximal realignment had recurrent patellar dislocation and received revision surgery for it. A total of 9 patients were evaluated, amongst them, two were returning patients whilst the others were new to our hospital. Again, the revision surgeries had been performed by a single surgeon (J.D.Y.). The study was performed in accordance to the Declaration of Helsinki. Informed consent was obtained from each participant before the investigation began, and no monetary compensation was provided. We identified a total of nine patients who underwent revision surgery. Amongst the 51 knees that had received surgery for the initial patellar dislocation, we found that only 2 knees, of the 20 that received a treatment of lateral retinacular release and medial imbrication, had required a revision surgery, which was medial patellofemoral ligament reconstruction. At the last follow-up (average, 16 months), we found that symptoms of instability were no longer seen. In contrast, none of the 31 knees that received a treatment of medial patellofemoral ligament reconstruction showed recurrence of instability at least until the last follow-up (average, 18.5 months). Amongst those that had received only proximal realignment for patellar dislocation, the following 5 pairs of revision-initial surgery were found: trochleoplasty after medial patellofemoral ligament reconstruction in 1 patient; tibial tuberosity transfer after medial patellofemoral ligament reconstruction in 2; tibial tuberosity transfer and medial patellofemoral ligament reconstruction after medial patellofemoral ligament repair in 3; and tibial tuberosity transfer, medial patellofemoral ligament reconstruction, and distal femoral varization osteotomy after arthroscopic lateral retinacular release in 1. A detailed summary of the patient demographic data is presented in Table 1. At the 1-year follow-up, we found that none of the patients needed a reoperation or developed complications. Table 1. Detailed demographic data of patients Gender Age (yr) TT-TG I/S ratio Trochlea dysplasia First operative Second operative F 18 22.1 1.34 B MPFL repair + LR Trochleoplasty + LR F 16 20.1 1.18 B LR + medial imbrication DFO + MPFLR + TTT M 28 20.0 1.16 B MPFL repair MPFLR + TTT M 20 21.1 1.15 No MPFL repair MPFLR + TTT F 25 19.2 1.10 No MPFL repair MPFLR + TTT F 21 21.5 1.09 No MPFL reconstruction TTT M 32 22.3 1.12 No MPFL reconstruction TTT M 26 16.2 1.06 No LR + medial imbrication MPFLR F 17 15.4 1.13 No LR + medial imbrication MPFLR F, female; M, male; TT-TG, tibial tuberosity-trochlear groove; I/S, Insall-Salvati ratio; MPFL, medial patellofemoral ligament; LR, lateral retinacular release; DFO, distal femur osteotomy; MPFLR, medial patellofemoral ligament reconstruction; TTT, tibial tubercle transfer. www.e-aosm.org 29
TT-TG :20.1 mm A B C D Fig. 1. (A) Preoperative scanogram of the whole lower extremity of Case 1 shows valgus alignment.(b) A preoperative tibial tuberosity-trochlear groove (TT-TG) distance of 20.1 mm was observed in Case 1. (C) Postoperative scanogram of the whole lower extremity (left) and intraoperative images of the medial patellofemoral ligament reconstruction (right) in Case 1. (D) Intraoperative images of the tibial tuberosity transfer in Case 1 are shown. 30 www.e-aosm.org
Case 1 A 16-year-old female patient was admitted to our clinic with symptoms of persistent instability. She had undergone lateral retinacular release and medial imbrication at another hospital 4 years ago, but despite treatment, she suffered from subluxation and recurrent instability after 1 year of surgery. Bone surgery was delayed on account of the open growth plate. As preoperative planning, we carried out simple radiography, which included taking a standing whole lower extremity scanogram and radiographs of the knee (true anteroposterior view; lateral view in 30 flexion; and the merchant view), and computed tomography. We found that the patient had a varus hipknee-ankle angle of 6 (Fig. 1A), a TT-TG distance of 20.1 mm (Fig. 1B), and a patella tilt of 52. As revision surgery, we performed distal femoral varization osteotomy, medial patellofemoral ligament reconstruction (Fig. 1C), tibial tuberosity medialization osteotomy, and lateral retinacular release (Fig. 1D). At the 1-year follow-up, we found that the hip-knee-ankle angle improved to a varus 2 and that the patella tilt improved to 15. Also, all instability-related symptoms were absent. Case 2 A 28-year-old male patient was admitted to our clinic for anterior knee pain during flexion, instability of the knee during gait, and difficulty in walking up the stairs. He had undergone arthroscopic lateral retinacular release and medial patellofemoral ligament advancement 10 years ago at a different hospital. However, the symptoms did not resolve. The same protocol for preoperative planning was used for Case 2 as in Case 1. We found that the patient had Type B trochlear dysplasia with patellofemoral arthritis (Fig. 2A), a varus hip-knee-ankle angle of 2, a TT- TG distance of 20.0 mm (Fig. 2B), and a patella tilt of 17. As revision surgery, we performed tibial tuberosity medialization osteotomy and lateral retinacular release (Fig. 2C) after which, although the J sign persisted, the symptoms of instability improved moderately. To address the residual symptoms, we performed a secondary medial patellofemoral ligament reconstruction 18 months after the initial surgery. The symptoms of instability and the J sign resolved after the secondary surgery and remained so until the 1-year follow-up. Case 3 An 18-year-old female patient was admitted to our clinic with recurrent patellar subluxation. She had undergone arthroscopic lateral retinacular release and medial patellofemoral ligament repair 7 years ago at another hospital. But subluxation and instability persisted even after surgery. The uniform protocol for preoperative planning was used as in Cases 1 and 2. We found that the patient had Type B trochlear dysplasia (Fig. 3A) with concomitant patella alta. Further, a valgus hip-knee-ankle angle of 3.5, a TT-TG distance of 22.1 mm (Fig. 3B), and a patella tilt of 25 were observed. The symptoms of instability resolved after we performed revision trochleoplasty and lateral retinacular release (Fig. 3C). At the 1-year follow-up, we found that the patella was well-positioned at the trochlea on the Merchant view (Fig. 3D). TT-TG :20.0 mm A B C Fig. 2. (A) Case 2 presented with Type B trochlear dysplasia with patellofemoral arthritis. (B) A preoperative tibial tuberosity-trochlear groove (TT-TG) distance of 20.0 mm was observed in Case 2. (C) An anteroposterior radiograph of the knee was taken after tibial tuberosity medicalization osteotomy and lateral release in Case 2. www.e-aosm.org 31
TT-TG :22.1 mm A B C D Fig. 3. (A) Case 3 presented with Type B trochlear dysplasia. (B) A preoperative tibial tuberosity-trochlear groove (TT- TG) distance of 22.1 mm was observed in Case 3. (C) Intraoperative images of trochleoplasty in Case 3 are shown. (D) Merchant view of Case 3 was taken at the 1-year postoperative follow-up. DISCUSSION A recurrent patellar dislocation is a common injury sustained by young, active patients, with nearly 70% of dislocations occurring during sports activities [7]. The risk of postoperative redislocation has been reported to be between 0% and 71% in young athletes. Until recently, the main surgical option for recurrent patellar dislocation was either lateral retinacular release and medial imbrication or medial patellofemoral ligament repair. But the poor clinical outcomes associated with these options have meant that new options must be sought. In our study, amongst the 20 knees that underwent lateral retinacular release and medial imbrication, 2 presented with recurrent instability upon trauma. No recurrent of instability was seen after medial patellofemoral ligament reconstruction. Of the 9 patients who received revision surgery, 6 patients had a TT-TG distance of 20 mm or greater. Indications for proximal realignment surgery alone for patellar dislocations are a normal Q angle, a normal patella height, and non-severe trochlear dysplasia. On the other hand, contraindications for proximal realignment-only are gross patellar instability, increased TT-TG distance of greater than 20 mm, severe trochlear dysplasia, lateral patella arthritis, and patella alta [2]. Lateral retinacular release is often performed concomitantly to proximal realignment. However, these procedures may sometimes increase the risk of postoperative instability, particularly medial patellar subluxation [8], and a postoperative complication of medial subluxation of the patella after lateral release may paradoxically worsen symptoms [9]. Thus, an inappropriate surgical indication especially that of lateral release may cause poorer outcomes [10]. When we evaluated the patients who had recurrent lateral patellar dislocation in spite of a previous proximal realignment, we found that 9 patients required revision surgery. The main reason for revision was patellar instability. All patients, except for 2, could not be indicated for proximal realignment surgery alone. On the basis of our experience, we deduced that the cause of failed proximal realignment was inadequate preoperative planning. The mean TT-TG distance of the 7 patients was 20.9 mm, and trochlear dysplasia was observed preoperatively in 3. Specifically, because Case 3 patient had a TT-TG distance of 22.1 mm and severe Type B trochlear dysplasia, we 32 www.e-aosm.org
performed sulcus deepening trocheoplasty without tibial tuberosity osteotomy on account of the reducing effect of trochleoplasty on TT-TG distance. In conclusion, it is very important to make a detailed preoperative evaluation when planning surgeries to address recurrent patellar dislocations. In light of our experience, the common causes of recurrent patellar dislocations usually pertains to inadequate preoperative planning, which often leads to an underestimated TT-TG distance. CONFLICT OF INTEREST No potential conflicts of interest relevant to this article are reported. REFERENCES 1. Mitchell J, Magnussen RA, Collins CL, et al. Epidemiology of patellofemoral instability injuries among high school athletes in the United States. Am J Sports Med 2015;43:1676-82. 2. Schneider DK, Grawe B, Magnussen RA, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med 2016;44:2993-3005. 3. Csintalan RP, Latt LD, Fornalski S, Raiszadeh K, Inacio MC, Fithian DC. Medial patellofemoral ligament (MPFL) reconstruction for the treatment of patellofemoral instability. J Knee Surg 2014;27:139-46. 4. Testa EA, Camathias C, Amsler F, Henle P, Friederich NF, Hirschmann MT. Surgical treatment of patellofemoral instability using trochleoplasty or MPFL reconstruction: a systematic review. Knee Surg Sports Traumatol Arthrosc 2015 Jul 18 [Epub]. https://doi.org/10.1007/s00167-015-3698-1. 5. Weber AE, Nathani A, Dines JS, et al. An algorithmic approach to the management of recurrent lateral patellar dislocation. J Bone Joint Surg Am 2016;98:417-27. 6. Arendt EA, Dejour D. Patella instability: building bridges across the ocean a historic review. Knee Surg Sports Traumatol Arthrosc 2013;21:279-93. 7. Fithian DC, Paxton EW, Stone ML, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med 2004;32:1114-21. 8. Christoforakis J, Bull AM, Strachan RK, Shymkiw R, Senavongse W, Amis AA. Effects of lateral retinacular release on the lateral stability of the patella. Knee Surg Sports Traumatol Arthrosc 2006;14:273-7. 9. Shannon BD, Keene JS. Results of arthroscopic medial retinacular release for treatment of medial subluxation of the patella. Am J Sports Med 2007;35:1180-7. 10. Song GY, Hong L, Zhang H, Zhang J, Li Y, Feng H. Iatrogenic medial patellar instability following lateral retinacular release of the knee joint. Knee Surg Sports Traumatol Arthrosc 2016;24:2825-30. www.e-aosm.org 33