“Comparative study on the Outcome Of Anatomical Anterior Cruciate Ligament Reconstruction Using Bone Patellar Tendon Bone Vs Hamstring Tendon Autograft At A Mean Follow Up Of 8 Years”

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 INTRODUCTION

  Anterior cruciate Ligament tear (ACL) is a common ligament injury of knee joint worldwide. Approximately one third of them develop persisting knee instability and osteoarthritis (OA) change over long term if not treated by surgery [1]. Anterior cruciate ligament reconstruction(ACLR) using autografts or allografts is the standard of treatment for complete ACL tear. In the last two decades concepts in ACLR evolved in terms of tunnel positioning, graft selection, fixation methods, timing of surgery from injury, postoperative rehabilitation and so on. Anatomical tunnel positioning provides a better rotational as well as anteroposterior stability following ACLR [2-3].Nevertheless, a well performed anatomical ACLR do fail due to various reasons. Among this graft selection may be one of the contributing factor. Though both autografts and allografts were being used commonly, majority of the studies favours autografts over allografts [4-5]. The most commonly studied autografts were Bone patellar tendon bone(BPTB) and Hamstring tendon (HT) autografts. Many studies favours  both the grafts with merits and demerits on each graft leaving a space for further study on  an ideal graft. Further, the debate on long term  OA changes using these two grafts  still remains unanswered[6-7].Most of the clinical studies comparing these two grafts in the past have not considered anatomical tunnel positions on the femoral and tibial side. This creates a scope for studying on the outcome of anatomically performed ACLR using these two grafts. This would possibly reduce or eliminate the confounding effect of non anatomical tunnel positions on the final outcome. Hence, we proposed to study  the influence of graft choice on clinico-radiological outcome following anatomical ACLR using BPTB and HT autografts.

 

METHODS:

Study design and ethics approval:

This was a single centre retrospective study conducted at a tertiary care hospital in South India. Institutional review board  approval and ethical committee  clearance was obtained for the study(IEC No. EC/NEW/INST/2021/2200). Data of patients  who had underwent primary arthroscopic ACLR during the period of January 2013 to January 2016  were selected from hospital registry . Patients with age between 18 and 50 of both sex, who had underwent single bundle ACLR for only isolated ACL tear using either BPTB or HT autografts were included for this study. Patients with associated meniscal injuries,  Kellegran and Lawrence (KL) Grade >2[8],multiligamentous knee injury, ipsilateral limb fractures , generalised ligament laxity and postoperative infections were excluded from the study.

Surgical procedure and postoperative rehabilitation:

The recruited patients who fulfilled the primary inclusion criteria had underwent   arthroscopic single bundle ACLR using either BPTB or Quadrupled HT autografts harvested from ipsilateral limb. A single fellowship trained arthroscopic surgeon performed the surgery in all  patients. Transportal technique (TP) was used for femoral tunnel creation. Titanium interference screws(stryker,USA) were used for both femoral and tibial side graft fixation .All the patients recruited for the study underwent  uniform postoperative rehabilitation as per hospital protocol.Informed consent was obtained from all individual participants included in the study.

Evaluation of Clinico-radiological outcome :

The selected cohort  were subjected to radiological survey to differentiate anatomical and nonanatomical ACLR. Plain radiography of both knees in Standing AP view with 0⁰ knee flexion, PA view with 30⁰ knee flexion and lateral view with 30⁰ knee flexion were taken. All radiograph  images were interpreted in DICOM format in PACS( version-8.2).The anatomical nature of reconstruction was assessed as per the radiological landmarks described by Pinczewski et al as shown in Fig-1[9].

Figure 1 : Plain Xray of knee joint showing Anatomical Tunnel Parameters and GIA (Pinczewski et al)

 

1A- Sagittal Tunnel Positions

1B -Coronal Tunnel Positions

1C- Graft Inclination Angle

 

Accordingly, the tunnel parameters analysed in the selected cohort were CFTP (coronal femoral tunnel position), SFTP(sagittal femoral tunnel position), CTTP(coronal tibial tunnel position), STTP(sagittal tibial tunnel position) and GIA(graft inclination angle). Patients  who found to have anatomical tunnel position and GIA were then evaluated for final analysis as shown in Fig-2.

Figure 2: Postoperative Xray showing Anatomical Tunnel Parameters and GIA in a patient enrolled for the study

2A- Sagittal Tunnel Positions

2B -Coronal Tunnel Positions

2C- Graft Inclination Angle  

Patients  who found to have  nonanatomical tunnel position and GIA were excluded from the study.Patients with anatomical ACLR were divided into two groups based on autograft used (BPTB group and HT group).Patients in each group were evaluated for clinical(subjective and objective) and radiological outcome   at their latest  followup. The outcome parameters used in the study were as follows:

I-Subjective clinical outcome parameters

1)International Knee Documentation Committee (IKDC)-subjective  scoring             

2)Lyshlom scoring             3)Anterior knee pain

II-Objective clinical outcome parameters

1)International Knee Documentation Committee (IKDC)-objective Grading           

2)Single leg hop test (SLHT)   3)Pivot shift test(PST) 4)Anterior drawer test(ADT)  5)Manual Lachman test(MLT)

III-Radiological outcome parameters

1)Radiological Laxometry test(RLT)             2)OA change.

 

The objective clinical parameters were graded as per IKDC knee examination form.

RLT was performed at 25⁰  of knee flexion using 134N (13.5 kgs) weight to quantitate the anteroposterior stability(modified J. L. Lerat method)[10].The contralateral uninjured knee served as reference for comparing the knee stability tests. The results of stability tests were graded as per IKDC knee scoring system. OA change assessed by comparing the preoperative weight bearing plain radiographs of injured knee with latest post operative plain radiograph  using  KL Grading. Radiological evaluation was done by 2 persons (Radiologists) with reliable inter  and intra observer correlation.From hospital registry 150 patients were enrolled for the study. They were subjected to radiological survey for tunnel positions and GIA. Among them, 88 patients comprising 40 BPTB group and 48 HT group had  anatomical ACLR. Remaining 62 subjects who had non anatomical tunnel positions and GIA in both groups were excluded from the study. Due to various reasons 8 patients out of 88 study subjects dropped out from the study leaving a total of 80(36 in BPTB and  44 in HT group).They were finally evaluated for clinico-radiological outcome measures. The flow chart of patient selection for the study shown in Fig-3.

Figure 3: Flow chart showing patient selection for the study

 

 

 

Statistical analysis:

A statistician performed all the data analyses using IBM SPSS Statistics (Version 23.0, IBM Corp, Armonk, New York, USA). Demographic variables were summarized with standard descriptive statistics, such as frequency, mean (standard deviation) or median (interquartile range). The subjective clinical outcome between the two groups were compared using Pearson’s chi-square test and Man-whitney test. Statistical difference between the two groups in terms of objective clinical and radiological outcome was performed with Student’s t-test. The level of significance was 5% (two-tailed) for all analyses. The clinical and radiological outcome parameters were dichotomised for the purpose of statistical analysis as shown in Table-1.

Table-1:Dichotomisation of Clinical and Radiological Outcome Parameters

Variable	Dichotomisation
Pivot shift test(PST)	Grade A
	Grade B ,C and  D
IKDC(Objective)	Grade A and B
	Grade C and D
Single leg hop test (SLHT)	Garde A and B
	Grade C and D
Anterior Drawers test(ADT)	Grade A
	Grade B,C and D
Manual Lachman test(MLT)	Grade A
	Grade B , C and D
Radiological Laxometry test ( RLT )	Grade A
	Grade B , C and D
KL(KELLGREN & LAWRENCE GRADE) Grade	Normal and Grade 1
	Grade 2,3 and 4

 

RESULTS:

A total 80 patients, comprising 36(45%)in BPTB and 44(55%) in HT group  were analysed for the clinico-radiological outcome. The results were analysed at mean follow up  of 8 years (+/- 2 years ) after ACLR .The mean (SD) age of the study subjects was observed to be 31.25 (6.83). Around 34 (42.5%), 32 (40%) and 14 (17.5%) belonged to the age group 20-29 years, 30-39 years and 40-49 years respectively. Male and female subjects accounted for 71 (88.8%) and 9 (11.3%) respectively. Road traffic accidents 34 (42.5%), self-fall 24 (30%) and sports injury 22 (27.5%) were reported to be the different modes of injury among the study subjects. The median time from injury was found to be 90 (30-180) days. The mean (SD) follow-up time for the patients was 98.59 (+/-13.78) months(8 years +/-2 years). The demographic profile between the two groups were comparable with no statistical difference as shown in Table-2.

Table 2 : Demographic profile of BPTB and HT group

DEMOGRAPHIC PROFILE	BPTB	HT	P value
Age	31.28	31.23	0.248
Sex         Male         Female	32 4	39 5	0.724
Time since injury (days)	144.64	128.23	0.241
Mechanism of injury          RTA(Road Traffic Accident)          Self-fall          Sports injury	15 10 11	19 14 11	0.881
Follow up time (months)	94.44	101.98	0.31732
Side of injury           Right           Left	20 16	26 18	0.971

 

Preoperative parameters :

The subjective , objective and radiological preoperative parameters were comparable between the two groups as shown in Table-3.

Table 3: Comparison of preoperative parameters between BPTB and HT group

Clinical and raiological  parameters	HT	BPTB	P value
PST
Grade A	1	1	0.886
Grade B,Cand D	43	35
Objective IKDC Score
Grade A and B	0	1	0.266
Grade C and D	44	35
SLHT
Garde A and B	2	0	0.279
Grade C and D	42	36
ADT
Grade A	1	1	0.886
Grade B,C and D	43	35
MLT
Grade A	2	0	0.195
Grade B ,C and D	42	36
RLT
Grade A	2	0	0.195
Grade B,C and D	42	36
KL Grading
Normal and Grade 1	40	34	0.550
Grade 2,3,4	4	2
IKDC (Subjective)
Mean	50.680	48.086	0.121
Minimum	6.9	33.3
Maximum	71.3	67.8
Std Deviation	10.7046	8.659
LYSHLOM Score			0.841
Mean	37.32	39.50
Minimum	2	24
Maximum	66	58
Std Deviation	12.0	10.953

 

The distribution of clinical and radiological outcome in the BPTB and HT groups are shown graphically in  Figure- 4 and Figure-5 .

Figure 4 : Distribution of objective clinical and radiological outcome  in BPTB group

Figure 5 : Distribution of objective clinical and radiological  outcome  in HT group

 

 

Postoperative clinical outcome:

There was no difference between the two groups in terms of Subjective Clinical outcome like postoperative IKDC (subjective ) score(p-value 0.154) , LYSHLOM score(p-value 0.894)   and Anterior Knee Pain(p-value 0.678) (Table-4).

Table 4: Comparison of postoperative subjective  clinical  outcome parameters between BPTB and HT group

Subjective clinical outcome parameters	HT	BPTB	P Value
IKDC (Sub)
Mean	90.361	92.019	0.154
Minimum	50	77
Maximum	98.9	97.7
Std Deviation	6.7138	5.1267
LYSHLOM Score
Mean	93.86	94.31	0.894
Minimum	50	85
Maximum	100	100
Std Deviation	5.147	4.439
Anterior knee pain
Present	1	2	0.678
Absent	43	34

 

There was no statistical difference between  the two groups in terms of  IKDC(objective) Grading (p-value 0.363) and  SLHT Grading(p-value 0.248),although two patients in HT group exhibited  Grade C IKDC(objective) and SLHT,while none in the BPTB group had Grade C with regard to these two parameters. In contrast, the objective clinical outcome in terms of postoperative PST, ADT and MLT were found to be superior in BPTB group over HT group(BPTB/HT) as follows :

PST-Grade A-31/5,Grade B-5/37 ,Grade C- 0/2

ADT-Grade A-34/3,Grade B-2/37, Grade C-0/4

MLT-Grade A-31/5,Grade B-5/37,Grade C- 0/2.

The difference was statistically  significant  in all these three parameters (p value - 0.001) as shown in Table -5.

 

Table 5: Comparison of postoperative objective  clinical  outcome parameters between BPTB and HT group

Objective clinical outcome parameters	HT	BPTB	P Value
PST
Grade A	5	31	0.001
Grade B,C and D	39	5
IKDC (Obj)
Grade A and B	43	36	0.363
Grade C and D	1	0
SLT
Garde A and B	41	36	0.248
Grade C and D	3	0
ADT
Grade A	3	34	0.001
Grade B , C and D	41	2
MLT
Grade A	5	31	0.001
Grade B, C and D	39	5

 

 

 

Post operative Radiological outcome:

The postoperative Laxometry test ( RLT ) assessment had shown better outcome in BPTB group compared to HT group(BPTB/HT) as follows: (Grade A -31/5,Grade B-5/37 and Grade C-0/2) and the difference was statistically significant(p-value 0.001). There was no difference in OA change  between the two groups(p-value 0.550) (Table-6).

Table 6: Comparison of postoperative radiological  outcome parameters between BPTB and HT group

Radiological outcome parameters	HT	BPTB	P Value
RLT
Grade A	5	31	0.001
Grade B,C and D	39	5
KL  Grading
Normal and Grade 1	40	34	0.550
Grade 2 ,3,4	4	2

 

Interestingly none of the patients had shown progression of OA at long term evaluation and the current postoperative KL Grading remains  same as that of their preoperative KL Grading  in all  the patients.

 

DISCUSSION:

 The primary finding in our study was that patients in BPTB group  shown superior clinical outcome over HT group in terms of improved rotational as well as anteroposterior stability. These results were statistically significant and more importantly the difference was found at mean follow up of 8 years (+/- 2 years)after ACLR. There was no difference between the two groups in terms of demography, fixation method, femoral and tibial tunnel drilling technique, IKDC score(objective and subjective),SLHT ,LYSHLOM score and OA change. The distinct feature of the current study was that, we evaluated the outcomes only in anatomically reconstructed ACL, in order to avoid confounding effect of nonanatomical tunnel parameters on the final outcome. Majority of the clinical studies in the past compared the outcome of BPTB and HT autografts either  at short term or  mid term(< 5 years) followup[11-13].Only  few studies  have long term followup of > 5 years [14-16].In all these  studies either the tunnel parameters were not considered or have not excluded  non anatomical tunnels using radiography when comparing these two garfts. The current study was distinct from above studies in that we aimed to compare the  outcome of these two grafts only in anatomically reconstructed ACL  using plain radiography at mean follow up of 8 years.

Michael C.Ciccotti et al[17],in their systemic review  on mid to long term follow up studies on anatomical ACLR via independent tunnel drilling(transportal technique) comparing BPTB and HT autografts found no difference between the grafts in terms of clinical outcome scores and graft failure rates. However they noted BPTB autograft  causes greater anterior knee pain and OA change. On the other side HT autografts shown increased laxity and  less knee flexion strength. They have not analysed tunnel parameters radiologically for confirming anatomical ACLR. They probably would have considered independent tunnel drilling  as a way of anatomical ACLR. In our study though all study subjects underwent ACLR by transportal technique, we did radiological evaluation of tunnel positions and GIA  to ensure only anatomical ACLR for comparing the outcome between these two grafts. In our study, we found no difference between these two grafts in terms of subjective outcome, but BPTB autograft shown a better rotational and anteroposterior stability over HT autograft. Although, many studies mentioned anterior knee pain was more so associated with BPTB autograft[17-19], the current study results shown only two patients in BPTB and one in HT group had  anterior knee pain and the difference was insignificant.Misty Suri et al[20] recently studied on anterior knee pain in patients who underwent ACLR using BPTB and found the functional anterior knee pain was less compared to literature using this graft.

Ricardo Cristiani et al [11] done a comparative study between BPTB and HT autografts on 5462 patients for knee laxity and patient reported outcome measures following primary ACLR. Their study showed greater anterior laxity and more surgical failures using HT autografts over BPTB autografts at 1 year follow up. Their study has no differentiation between anatomical and non anatomical tunnel positions. Our study results also shown similar results,but more importantly at a mean  followup of 8 years in anatomical ACLR.

Pinczewski et al [10]reported a significantly higher incidence of radiographic arthritic changes in the BPTB group compared with the HT group in their long-term prospective study. In a midterm study Keays SL et al[21] found a significantly higher incidence of tibiofemoral osteoarthritis in the BPTB group (62% BPTB vs 33% HT). Inger Holm et al[6] at ten years of follow up compared BPTB and HT autografts. They found that the prevalence of osteoarthritis was significantly higher in the operated leg than in the contralateral leg, but there were no significant differences between the two groups. They concluded that the choice of graft type after an anterior cruciate ligament injury has minimal influence on the prevalence of osteoarthritis ten years after surgery. In the current study , we could not find any difference between the grafts in terms of OA changes at a mean followup of 8 years. In our study,Patients who had no OA change at the time surgery found to have no OA change in the operated knee in both the groups. Interestingly patients who had preexisting Grade1 and Grade 2 OA changes at surgery also did not show any detoriation of OA change at their latest follow up in both groups .Similar results were shown  in other studies also[22-23].This indicate that apart from graft selection other factors  like tunnel parameters, concomitant meniscal or chondral injuries may be a major contributary factor for OA changes as described in previous studies[24].Since our study population had no concomitant meniscal or focal chondral injuries, the above findings may be attributed to this. Another possible reason  could be that we used transportal technique in all our patients. Studies have shown anatomical ACLR using TP technique resulted in less OA changes at long term follow up[23-24].It was shown in previous studies that patients who underwent ACLR using transtibial (TT) technique demonstrated OA change at long term follow up than TP technique. Bjorn Barenius et al[25] in their study found more than half of transtibial ACLR patients demonstrated radiographic evidence of Grade 2 or higher joint degenerative changes at 14 years.Similarly,Pinczewski et al.[10] performed a  study on 200 patients who underwent ACL reconstruction for clinical and radiological assessment at  7 years followup. The authors  reported that a more vertical graft in the coronal plane was  significantly correlated to inferior rotational stability and  an increased level of OA. Since, we excluded non anatomical ACLR  in our study, we obviously eliminated vertical grafts. This  could be another possible reason for  absence of OA changes in our study population.

The strength of our study was that we compared the results of two grafts only in patients with anatomical ACLR. Many studies had shown anatomical ACLR would result in superior long term clinical outcome and low graft failures[2-3]. Hence,we believed that by excluding non anatomical ACLR in the study population one could eliminate the confounding effect of tunnel positions on final outcome, making the comparability meaningful.In order to achieve the anatomical ACLR  one should place the femoral and tibial tunnels in centre of the native foot prints.Though it was argued that transportal drilling would aid in achieving anatomical ACLR on the femoral side, one cannot assume that all patients with this technique will have anatomical ACLR, as studies have shown that non anatomical femoral tunnel placement equally exist in both TP and TT technique[26].On the tibial side anatomical tibial tunnel position in ACLR would be difficult to judge by preop images, intraoperative arthroscopy landmarks or intraoperative fluoroscopy[27-28]. Hence,we believe that best way to assess the anatomical ACLR is to evaluate  using post operative plain Xray or CT scan. Though  CT scan has more precision among the two, higher radiation exposure and cost precludes its use in our part of the globe. Hence, we used only plain radiography in the current study to evaluate tunnel positions  as described by PINCEWZKI et al[10] to include  only those subjects who had tunnel parameters in the anatomical range for comparing the outcome of two grafts. Patrick Sadhogi et al[2]did comparative study on clinical outcome between BPTB and HT autografts using post operative 3 D CT images for assessing tunnel positions and found anatomical tunnel positioning shown better clinical outcome. Although they used CT images for assessing tunnel positions, their study did not excluded nonanatomical ACLR from their study. They compared single bundle(SB)-BPTB and double bundle(DB)-HT autografts unlike we compared SB-BPTB and SB- HT autografts in our study. Further their study period was only one year as against our study which has 8 years mean follow up.

Our study has several limitations. We performed a retrospective study, having a retrospective data collection. Hence a possible selection bias of study population was unavoidable. Though we attempted to exclude non anatomical tunnels using plain radiography, the accuracy of this method needs to be validated, as subtle rotations of knee joint in plain radiography is possible.As we compared the two grafts ,the graft diameter was not comparable as HT autograft group had more graft diameter variability from 7to 10 mm as opposed to BPTB group which had constant 9 or 10 mm graft diameter in all patients. We did not compared other outcome parameters like time taken for return to sports or return to preinjury level between the two groups which has a implication on early graft incorporation. The other limitation in our study was that we have not assessed the rotational or anteroposterior stablitity by instrumented arthrometers like KT-1000 Arthrometer, although we used stress radiography in all the study population and compared to contralateral knee for anteroposterior stability (RLT).

 

CONCLUSION:

        BPTB autografts had shown superior clinical outcome over HT autografts  in terms rotational and AP  knee stability at mean follow up of 8 years after anatomical ACLR. There was no difference between these two grafts in terms of  other clinical parameters and OA change. Future long term prospective randomised studies on this subject is recommended to validate our results.

 

 

 

 

 

About the authors

THATCHINAMOORTHY SANTHAMOORTHY

Specialist in orthopaedics,
Department of orthopaedics,
Indhira gandhi governtment general hospital and post graduate institute.

Author for correspondence.
Email: santhamoorthyt@yahoo.com
Индия, No.1 victor Simonel street, Puducherry-605001,INDIA

ANISH ANTO XAVIER

DNB resident
Department of orthopaedics
Indhira gandhi governtment general hospital and post graduate institute

Email: dr.anishxavier@gmail.com
No.1 victor Simonel street, Puducherry-605001,INDIA

CHELLAMUTHU LALITHAMBIGAI

Assistant Professor ,
Department of community medicine,
Mahatma gandhi medical college and research institute.

Email: Lalli.muthu@gmail.com
Pilliyarkuppam, Puducherry -607402 , INDIA

KALIAPERUMAL ARUN

Associate professor,
Department of orthopaedics,
Indhira gandhi medical college and research institute.

Email: karun83@gmail.com
kadirkamam, Puducherry-605009, INDIA

Dharmveer kumar Dubey

Specialist in orthopaedics,
Head of the department,
Department of orthopaedics,
Indhira gandhi governtment general hospital and post graduate institute.

Email: dk64dubey@yahoo.co.in
No.1 victor Simonel street, Puducherry-605001, INDIA

References

Supplementary files