Modified Kocher-Langenbeck approach for the treatment of posterior wall or column acetabular fractures: The one-incision two-window method

( a ) Indicate the study’s design with a commonly used term in the title or the abstract ( b ) Provide in the abstract an informative and balanced summary of what was done and what was found background and for the investigation Abstract Background: The Kocher-Langenbeck (K-L) approach is the standard method for the treatment of posterior wall or column acetabular fractures. This approach allows direct access to the posterior structures of the acetabulum, but is limited cranially and caudally by the neurovascular bundle. The present study was conducted to assess the quality of reduction and the incidence of complications in patients who underwent the modified (cid:9) “one-incision two-window” K-L approach. Design: Retrospective case series. modified two-window”


Introduction
Background/rationale 2 Explain the scientific background and rationale for the investigation being Describe any efforts to address potential sources of bias 7 Study size 10 Explain how the study size was arrived at 7 Quantitative variables 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why

Conclusions:
Our pilot study confirmed that the "one-incision two-window" K-L approach is a simple, safe, reliable, and effective way to manage acute, displaced posterior wall or column acetabular fractures.
Level of evidence: Therapeutic study, level IV. nonunion, and neurovascular injury still tend to diminish the treatment outcome of acetabular fractures despite adequate surgical exposure of the operative field for good fracture reduction and rigid fixation. [9][10][11] The current study reviews our experience with a modification of the K-L approach in the treatment of acute, displaced posterior wall or column acetabular fractures. The modification involves a minimally invasive approach by which the neurovascular bundles are well protected from undue traction or damage by avoiding vigorous retraction. The study was conducted to assess the quality of reduction and the incidence of complications in patients who underwent the modified "one-incision two-window" K-L surgical approach.

Surgical technique (Fig. 1)
The patient is placed in a lateral decubitus position with the affected side uppermost.
No skeletal traction is applied to the injured hip. In line with the longitudinal axis of the femur, skin incision is started 5 cm distal to the posterior tip of greater trochanter (PTGT).
After passing the PTGT, the skin incision is continued 5 cm further in the direction of the posterior superior iliac spine. The iliotibial tract is divided sharply in line with its fibers, and the gluteus maximus muscle is split bluntly along the raphe, which indicates the inter-neurovascular interval between the SGB and the inferior gluteal neurovascular bundle for the upper one-third and lower two-third of the gluteus maximus muscle, respectively.
After removing the layer of fat and bursa covering the SERs, the insertions of the piriformis tendon and the conjoined tendon of the gemellus and obturator internus muscles are meticulously identified and divided 1 cm lateral from their femoral insertions to protect the MCFA, which helps supply blood to the neck and head of the femur. By retracting the divided tendon stumps gently, the first window is created to expose the posterior wall, ischial body, and ischial tuberosity. In this window, the displaced fracture fragments can be

Participating patients and study significance
Between January 2015 and December 2017, a total of 13 consecutive patients (10 men and 3 women) were treated by a single surgeon (TTY) for acute, displaced posterior wall or column acetabular fractures by using the modified "one-incision two-window" K-L surgical approach. Among these patients, seven had transverse with or without posterior wall acetabular fracture and six had posterior wall acetabular fracture alone. At the time of study enrollment, we summarized the collected data, which included demographic characteristics, fracture pattern, surgery details, and radiographic and clinical outcome measurements, among others. These data were analyzed to study the effectiveness of the modified "one-incision two-window" K-L surgical approach in the treatment of acute, displaced posterior wall or column acetabular fractures. The modification involves a minimally invasive approach that is believed to provide a simple, safe, reliable, and effective way to manage these complex lesions.

Radiographic and clinical outcome measurements
Regular radiographic and clinical assessments were carried out immediately before and after surgery -that is, preoperatively; immediately after surgery; and at 1, 2, 3, 6, and rate. 18 The mean follow-up period averaged 20.6 months (range, 12-36 months).

Statistical analysis
Between-group comparisons were performed using univariable analysis.
Mann-Whitney U-test and Fisher's exact test were used to analyze numerical and nominal variables, respectively. Significance was set at P < 0.05 (two-sided). SPSS 12.0 (SPSS Inc., Chicago, IL, USA) was used for all analyses.

Ethics statement
The data were analyzed after the approval by the ethics committee (institutional review board) of Chang Gung Memorial Hospital, Taiwan (reference no. 201801360B0). (Table 1) In this 3-year-long study, we enrolled 13 patients who underwent the modified  (Table 2) With respect to the quality of fracture reduction, we measured the MRD of the walls and columns on plain radiographs taken immediately after surgery. We found that none of the residual wall or column fracture displacements were > 2 mm; thus, the radiographic quality of reduction was graded as anatomical reduction (MRD ≤ 2  Because of failed conservative treatment, the patient with advanced PTOA underwent total hip arthroplasty (THA) at 6 months after posterior wall acetabular fracture dislocation. (Table 3) After

Discussion
Our pilot study revealed that the modified "one-incision two-window" K-L surgical approach is a simple, safe, reliable, and effective way to manage acute, displaced posterior wall or column acetabular fractures. The proposed approach used a curved skin incision averaging 9.7 cm (range, 8-13 cm) in length and provided an adequate working space for manipulation by the surgeon even in patients with severe obesity (SDC 1). Within the first window, fractured lesions were well exposed, reduced, and fixed provisionally. The The aim of surgical treatment of displaced acetabular fractures is to establish a stable anatomical reduction with a functional, mobile, and pain-free hip. 13,14 The accuracy of fracture reduction and internal fixation correlates strongly with functional outcomes. 10,15 The conventional K-L approach is the standard method for posterior wall and column acetabular fractures; however, access to the superior wall area is limited. 7 By using this approach, Matta reported an 80% anatomical reduction rate for transverse posterior wall acetabular fracture types, and fair or poor clinical results as measured using the d'Aubigne score in 30% of cases. 1  and easier fixation of the cranial acetabular fragments; however, the more extensile the approach used, the higher the rate of associated surgical risk and complications. For example, trochanteric nonunion is believed to occur in 2%-15% of cases following trochanteric osteotomy. 21 Without adding a bone or soft tissue procedure to the conventional K-L approach, vigorous manipulations for visualization, reduction of the fractured fragments, and even screw fixation of a bridging plate may lead to substantial stretching and laceration of the surrounding soft tissues, which subsequently may contribute to iatrogenic neurovascular injuries, HO, ONFH, and SSIs, among others. [22][23][24] A 2% rate of intervention-related nerve injury (IRNI) associated with acetabular fractures was reported in a retrospective study of prospectively collected data from the German Pelvic Trauma Registry. 23 In that 12-year-long study including a total of 2236 patients from 29 hospitals, Lehmann et al. found that the K-L approach was associated with the highest proportion of IRNIs. 23 Apart from the SN, which is typically injured in posterior approaches, the inferior ramification of the deep SGB is considered at risk when the gluteal muscles is retracted > 3 cm above the greater trochanter. [23][24][25] Likewise, vigorous retraction might increase soft tissue injury, lead to necrotic muscle in the injury zone, and increase the incidence of HO and SSIs. 26 Some researchers have suggested a modification involving sparing the division of the SERs, and declared that it could prevent iatrogenic damage to the MCFA and thus reduce the risk of secondary ONFH. 5,6 However, there was no direct evidence supporting this hypothesis.
Our proposed technique provided two working windows for surgical manipulation. This study has several limitations. First, this pilot study was a retrospective case series study with a small number of patients. Additionally, there was no control group for comparison to provide reliable evidence for the superiority of the proposed technique.
Second, although the major fracture prototype was a posterior wall or column fracture, several specific types of acetabular fractures were diagnosed in the current study. This could cause bias while analyzing the data, produces false conclusions, and is potentially misleading. Prospectively randomized controlled trials are needed in the future to compare this modified technique with the conventional approach for the specified fracture type.

Conclusion
This study introduced a modified K-L approach -the one-incision two-window method.